bug 4355 - improve parse exception messages

36 files changed, 693 insertions, 384 deletions

diff --git a/cpp/include/IceUtil/StringUtil.h b/cpp/include/IceUtil/StringUtil.h
index 4efd077dfb7..cb39efc02e5 100644
--- a/cpp/include/IceUtil/StringUtil.h
+++ b/cpp/include/IceUtil/StringUtil.h
@@ -23,9 +23,10 @@ namespace IceUtilInternal
 ICE_UTIL_API std::string escapeString(const std::string&, const std::string&);
 
 //
-// Remove escape sequences added by escapeString.
+// Remove escape sequences added by escapeString. Throws IllegalArgumentException
+// for an invalid input string.
 //
-ICE_UTIL_API bool unescapeString(const std::string&, std::string::size_type, std::string::size_type, std::string&);
+ICE_UTIL_API std::string unescapeString(const std::string&, std::string::size_type, std::string::size_type);
 
 //
 // Split a string using the given delimiters. Considers single and double quotes;
diff --git a/cpp/src/Ice/DefaultsAndOverrides.cpp b/cpp/src/Ice/DefaultsAndOverrides.cpp
index 81572b0ec68..587b9d79717 100644
--- a/cpp/src/Ice/DefaultsAndOverrides.cpp
+++ b/cpp/src/Ice/DefaultsAndOverrides.cpp
@@ -86,7 +86,7 @@ IceInternal::DefaultsAndOverrides::DefaultsAndOverrides(const PropertiesPtr& pro
     else
     {
         EndpointSelectionTypeParseException ex(__FILE__, __LINE__);
-        ex.str = value;
+        ex.str = "illegal value `" + value + "'; expected `Random' or `Ordered'";
         throw ex;
     }
 
diff --git a/cpp/src/Ice/EndpointFactoryManager.cpp b/cpp/src/Ice/EndpointFactoryManager.cpp
index 0c1e823712e..516f9dbbc44 100644
--- a/cpp/src/Ice/EndpointFactoryManager.cpp
+++ b/cpp/src/Ice/EndpointFactoryManager.cpp
@@ -72,7 +72,7 @@ IceInternal::EndpointFactoryManager::create(const string& str, bool oaEndpoint)
     if(beg == string::npos)
     {
         EndpointParseException ex(__FILE__, __LINE__);
-        ex.str = str;
+        ex.str = "value has no non-whitespace characters";
         throw ex;
     }
 
diff --git a/cpp/src/Ice/Instance.cpp b/cpp/src/Ice/Instance.cpp
index 24540c65491..f42191c8246 100644
--- a/cpp/src/Ice/Instance.cpp
+++ b/cpp/src/Ice/Instance.cpp
@@ -406,7 +406,7 @@ IceInternal::Instance::stringToIdentity(const string& s) const
                 // Extra unescaped slash found.
                 //
                 IdentityParseException ex(__FILE__, __LINE__);
-                ex.str = s;
+                ex.str = "unescaped backslash in identity `" + s + "'";
                 throw ex;
             }
         }
@@ -415,27 +415,39 @@ IceInternal::Instance::stringToIdentity(const string& s) const
 
     if(slash == string::npos)
     {
-        if(!IceUtilInternal::unescapeString(s, 0, s.size(), ident.name))
+        try
+        {
+            ident.name = IceUtilInternal::unescapeString(s, 0, s.size());
+        }
+        catch(const IceUtil::IllegalArgumentException& e)
         {
             IdentityParseException ex(__FILE__, __LINE__);
-            ex.str = s;
+            ex.str = "invalid identity name `" + s + "': " + e.reason();
             throw ex;
         }
     }
     else
     {
-        if(!IceUtilInternal::unescapeString(s, 0, slash, ident.category))
+        try
+        {
+            ident.category = IceUtilInternal::unescapeString(s, 0, slash);
+        }
+        catch(const IceUtil::IllegalArgumentException& e)
         {
             IdentityParseException ex(__FILE__, __LINE__);
-            ex.str = s;
+            ex.str = "invalid category in identity `" + s + "': " + e.reason();
             throw ex;
         }
         if(slash + 1 < s.size())
         {
-            if(!IceUtilInternal::unescapeString(s, slash + 1, s.size(), ident.name))
+            try
+            {
+                ident.name = IceUtilInternal::unescapeString(s, slash + 1, s.size());
+            }
+            catch(const IceUtil::IllegalArgumentException& e)
             {
                 IdentityParseException ex(__FILE__, __LINE__);
-                ex.str = s;
+                ex.str = "invalid name in identity `" + s + "': " + e.reason();
                 throw ex;
             }
         }
diff --git a/cpp/src/Ice/ObjectAdapterI.cpp b/cpp/src/Ice/ObjectAdapterI.cpp
index 69363ee91db..2c1ad771e36 100644
--- a/cpp/src/Ice/ObjectAdapterI.cpp
+++ b/cpp/src/Ice/ObjectAdapterI.cpp
@@ -1213,7 +1213,7 @@ Ice::ObjectAdapterI::parseEndpoints(const string& endpts, bool oaEndpoints) cons
         if(endp == 0)
         {
             EndpointParseException ex(__FILE__, __LINE__);
-            ex.str = s;
+            ex.str = "invalid object adapter endpoint `" + s + "'";
             throw ex;
         }
         endpoints.push_back(endp);
diff --git a/cpp/src/Ice/OpaqueEndpointI.cpp b/cpp/src/Ice/OpaqueEndpointI.cpp
index 9960872df1c..e4b1ee75215 100644
--- a/cpp/src/Ice/OpaqueEndpointI.cpp
+++ b/cpp/src/Ice/OpaqueEndpointI.cpp
@@ -46,7 +46,7 @@ IceInternal::OpaqueEndpointI::OpaqueEndpointI(const string& str)
         if(option.length() != 2 || option[0] != '-')
         {
             EndpointParseException ex(__FILE__, __LINE__);
-            ex.str = "opaque " + str;
+            ex.str = "expected an endpoint option but found `" + option + "' in endpoint `opaque " + str + "'";
             throw ex;
         }
 
@@ -67,16 +67,34 @@ IceInternal::OpaqueEndpointI::OpaqueEndpointI(const string& str)
         {
             case 't':
             {
+                if(argument.empty())
+                {
+                    EndpointParseException ex(__FILE__, __LINE__);
+                    ex.str = "no argument provided for -t option in endpoint `opaque " + str + "'";
+                    throw ex;
+                }
                 istringstream p(argument);
                 Ice::Int t;
-                if(!(p >> t) || !p.eof() || t < 0 || t > 65535)
+                if(!(p >> t) || !p.eof())
                 {
                     EndpointParseException ex(__FILE__, __LINE__);
-                    ex.str = "opaque " + str;
+                    ex.str = "invalid timeout value `" + argument + "' in endpoint `opaque " + str + "'";
+                    throw ex;
+                }
+                else if(t < 0 || t > 65535)
+                {
+                    EndpointParseException ex(__FILE__, __LINE__);
+                    ex.str = "timeout value `" + argument + "' out of range in endpoint `opaque " + str + "'";
                     throw ex;
                 }
                 _type = static_cast<Ice::Short>(t);
                 ++topt;
+                if(topt > 1)
+                {
+                    EndpointParseException ex(__FILE__, __LINE__);
+                    ex.str = "multiple -t options in endpoint `opaque " + str + "'";
+                    throw ex;
+                }
                 break;
             }
 
@@ -85,7 +103,7 @@ IceInternal::OpaqueEndpointI::OpaqueEndpointI(const string& str)
                 if(argument.empty())
                 {
                     EndpointParseException ex(__FILE__, __LINE__);
-                    ex.str = "opaque " + str;
+                    ex.str = "no argument provided for -v option in endpoint `opaque " + str + "'";
                     throw ex;
                 }
                 for(string::size_type i = 0; i < argument.size(); ++i)
@@ -93,27 +111,43 @@ IceInternal::OpaqueEndpointI::OpaqueEndpointI(const string& str)
                     if(!Base64::isBase64(argument[i]))
                     {
                         EndpointParseException ex(__FILE__, __LINE__);
-                        ex.str = "opaque " + str;
+                        ostringstream ostr;
+                        ostr << "invalid base64 character `" << argument[i] << "' (ordinal " << (int)argument[i]
+                             << ") in endpoint `opaque " << str << "'";
+                        ex.str = ostr.str();
                         throw ex;
                     }
                 }
                 const_cast<vector<Byte>&>(_rawBytes) = Base64::decode(argument);
                 ++vopt;
+                if(vopt > 1)
+                {
+                    EndpointParseException ex(__FILE__, __LINE__);
+                    ex.str = "multiple -v options in endpoint `opaque " + str + "'";
+                    throw ex;
+                }
                 break;
             }
 
             default:
             {
                 EndpointParseException ex(__FILE__, __LINE__);
-                ex.str = "opaque " + str;
+                ex.str = "invalid option `" + option + "' in endpoint `opaque " + str + "'";
                 throw ex;
             }
         }
     }
-    if(topt != 1 || vopt != 1)
+
+    if(topt != 1)
+    {
+        EndpointParseException ex(__FILE__, __LINE__);
+        ex.str = "no -t option in endpoint `opaque " + str + "'";
+        throw ex;
+    }
+    if(vopt != 1)
     {
         EndpointParseException ex(__FILE__, __LINE__);
-        ex.str = "opaque " + str;
+        ex.str = "no -v option in endpoint `opaque " + str + "'";
         throw ex;
     }
 }
diff --git a/cpp/src/Ice/ReferenceFactory.cpp b/cpp/src/Ice/ReferenceFactory.cpp
index fb6c0d0327d..2881e3953a3 100644
--- a/cpp/src/Ice/ReferenceFactory.cpp
+++ b/cpp/src/Ice/ReferenceFactory.cpp
@@ -110,7 +110,7 @@ IceInternal::ReferenceFactory::create(const string& str, const string& propertyP
     if(beg == string::npos)
     {
         ProxyParseException ex(__FILE__, __LINE__);
-        ex.str = str;
+        ex.str = "no non-whitespace characters found in `" + s + "'";
         throw ex;
     }
     
@@ -123,7 +123,7 @@ IceInternal::ReferenceFactory::create(const string& str, const string& propertyP
     if(end == string::npos)
     {
         ProxyParseException ex(__FILE__, __LINE__);
-        ex.str = str;
+        ex.str = "mismatched quotes around identity in `" + s + "'";
         throw ex;
     }
     else if(end == 0)
@@ -145,7 +145,7 @@ IceInternal::ReferenceFactory::create(const string& str, const string& propertyP
     if(beg == end)
     {
         ProxyParseException ex(__FILE__, __LINE__);
-        ex.str = str;
+        ex.str = "no identity in `" + s + "'";
         throw ex;
     }
 
@@ -174,7 +174,7 @@ IceInternal::ReferenceFactory::create(const string& str, const string& propertyP
         else if(s.find_first_not_of(delim, end) != string::npos)
         {
             ProxyParseException ex(__FILE__, __LINE__);
-            ex.str = str;
+            ex.str = "invalid characters after identity in `" + s + "'";
             throw ex;
         }
         else
@@ -216,7 +216,7 @@ IceInternal::ReferenceFactory::create(const string& str, const string& propertyP
         if(option.length() != 2 || option[0] != '-')
         {
             ProxyParseException ex(__FILE__, __LINE__);
-            ex.str = str;
+            ex.str = "expected a proxy option but found `" + option + "' in `" + s + "'";
             throw ex;
         }
 
@@ -236,7 +236,7 @@ IceInternal::ReferenceFactory::create(const string& str, const string& propertyP
                 if(end == string::npos)
                 {
                     ProxyParseException ex(__FILE__, __LINE__);
-                    ex.str = str;
+                    ex.str = "mismatched quotes around value for " + option + " option in `" + s + "'";
                     throw ex;
                 }
                 else if(end == 0)
@@ -268,14 +268,18 @@ IceInternal::ReferenceFactory::create(const string& str, const string& propertyP
                 if(argument.empty())
                 {
                     ProxyParseException ex(__FILE__, __LINE__);
-                    ex.str = str;
+                    ex.str = "no argument provided for -f option in `" + s + "'";
                     throw ex;
                 }
 
-                if(!IceUtilInternal::unescapeString(argument, 0, argument.size(), facet))
+                try
+                {
+                    facet = IceUtilInternal::unescapeString(argument, 0, argument.size());
+                }
+                catch(const IceUtil::IllegalArgumentException& e)
                 {
                     ProxyParseException ex(__FILE__, __LINE__);
-                    ex.str = str;
+                    ex.str = "invalid facet in `" + s + "': " + e.reason();
                     throw ex;
                 }
 
@@ -288,7 +292,7 @@ IceInternal::ReferenceFactory::create(const string& str, const string& propertyP
                 if(!argument.empty())
                 {
                     ProxyParseException ex(__FILE__, __LINE__);
-                    ex.str = str;
+                    ex.str = "unexpected argument `" + argument + "' provided for -t option in `" + s + "'";
                     throw ex;
                 }
                 mode = Reference::ModeTwoway;
@@ -300,7 +304,7 @@ IceInternal::ReferenceFactory::create(const string& str, const string& propertyP
                 if(!argument.empty())
                 {
                     ProxyParseException ex(__FILE__, __LINE__);
-                    ex.str = str;
+                    ex.str = "unexpected argument `" + argument + "' provided for -o option in `" + s + "'";
                     throw ex;
                 }
                 mode = Reference::ModeOneway;
@@ -312,7 +316,7 @@ IceInternal::ReferenceFactory::create(const string& str, const string& propertyP
                 if(!argument.empty())
                 {
                     ProxyParseException ex(__FILE__, __LINE__);
-                    ex.str = str;
+                    ex.str = "unexpected argument `" + argument + "' provided for -O option in `" + s + "'";
                     throw ex;
                 }
                 mode = Reference::ModeBatchOneway;
@@ -324,7 +328,7 @@ IceInternal::ReferenceFactory::create(const string& str, const string& propertyP
                 if(!argument.empty())
                 {
                     ProxyParseException ex(__FILE__, __LINE__);
-                    ex.str = str;
+                    ex.str = "unexpected argument `" + argument + "' provided for -d option in `" + s + "'";
                     throw ex;
                 }
                 mode = Reference::ModeDatagram;
@@ -336,7 +340,7 @@ IceInternal::ReferenceFactory::create(const string& str, const string& propertyP
                 if(!argument.empty())
                 {
                     ProxyParseException ex(__FILE__, __LINE__);
-                    ex.str = str;
+                    ex.str = "unexpected argument `" + argument + "' provided for -D option in `" + s + "'";
                     throw ex;
                 }
                 mode = Reference::ModeBatchDatagram;
@@ -348,7 +352,7 @@ IceInternal::ReferenceFactory::create(const string& str, const string& propertyP
                 if(!argument.empty())
                 {
                     ProxyParseException ex(__FILE__, __LINE__);
-                    ex.str = str;
+                    ex.str = "unexpected argument `" + argument + "' provided for -s option in `" + s + "'";
                     throw ex;
                 }
                 secure = true;
@@ -358,7 +362,7 @@ IceInternal::ReferenceFactory::create(const string& str, const string& propertyP
             default:
             {
                 ProxyParseException ex(__FILE__, __LINE__);
-                ex.str = str;
+                ex.str = "unknown option `" + option + "' in `" + s + "'";
                 throw ex;
             }
         }
@@ -439,8 +443,9 @@ IceInternal::ReferenceFactory::create(const string& str, const string& propertyP
             }
             if(endpoints.size() == 0)
             {
+                assert(!unknownEndpoints.empty());
                 EndpointParseException ex(__FILE__, __LINE__);
-                ex.str = unknownEndpoints.front();
+                ex.str = "invalid endpoint `" + unknownEndpoints.front() + "' in `" + s + "'";
                 throw ex;
             }
             else if(unknownEndpoints.size() != 0 &&
@@ -464,7 +469,7 @@ IceInternal::ReferenceFactory::create(const string& str, const string& propertyP
             if(beg == string::npos)
             {
                 ProxyParseException ex(__FILE__, __LINE__);
-                ex.str = str;
+                ex.str = "missing adapter id in `" + s + "'";
                 throw ex;
             }
 
@@ -473,7 +478,7 @@ IceInternal::ReferenceFactory::create(const string& str, const string& propertyP
             if(end == string::npos)
             {
                 ProxyParseException ex(__FILE__, __LINE__);
-                ex.str = str;
+                ex.str = "mismatched quotes around adapter id in `" + s + "'";
                 throw ex;
             }
             else if(end == 0)
@@ -496,14 +501,24 @@ IceInternal::ReferenceFactory::create(const string& str, const string& propertyP
             if(end != string::npos && s.find_first_not_of(delim, end) != string::npos)
             {
                 ProxyParseException ex(__FILE__, __LINE__);
-                ex.str = str;
+                ex.str = "invalid trailing characters after `" + s.substr(0, end + 1) + "' in `" + s + "'";
                 throw ex;
             }
 
-            if(!IceUtilInternal::unescapeString(adapterstr, 0, adapterstr.size(), adapter) || adapter.size() == 0)
+            try
+            {
+                adapter = IceUtilInternal::unescapeString(adapterstr, 0, adapterstr.size());
+            }
+            catch(const IceUtil::IllegalArgumentException& e)
+            {
+                ProxyParseException ex(__FILE__, __LINE__);
+                ex.str = "invalid adapter id in `" + s + "': " + e.reason();
+                throw ex;
+            }
+            if(adapter.size() == 0)
             {
                 ProxyParseException ex(__FILE__, __LINE__);
-                ex.str = str;
+                ex.str = "empty adapter id in `" + s + "'";
                 throw ex;
             }
 
@@ -515,7 +530,7 @@ IceInternal::ReferenceFactory::create(const string& str, const string& propertyP
         default:
         {
             ProxyParseException ex(__FILE__, __LINE__);
-            ex.str = str;
+            ex.str = "malformed proxy `" + s + "'";
             throw ex;
         }
     }
@@ -771,7 +786,7 @@ IceInternal::ReferenceFactory::create(const Identity& ident,
             else
             {
                 EndpointSelectionTypeParseException ex(__FILE__, __LINE__);
-                ex.str = type;
+                ex.str = "illegal value `" + type + "'; expected `Random' or `Ordered'";
                 throw ex;
             }
         }
diff --git a/cpp/src/Ice/TcpEndpointI.cpp b/cpp/src/Ice/TcpEndpointI.cpp
index c8e027b4ffb..3ac47c875bc 100644
--- a/cpp/src/Ice/TcpEndpointI.cpp
+++ b/cpp/src/Ice/TcpEndpointI.cpp
@@ -62,7 +62,7 @@ IceInternal::TcpEndpointI::TcpEndpointI(const InstancePtr& instance, const strin
         if(option.length() != 2 || option[0] != '-')
         {
             EndpointParseException ex(__FILE__, __LINE__);
-            ex.str = "tcp " + str;
+            ex.str = "expected an endpoint option but found `" + option + "' in endpoint `tcp " + str + "'";
             throw ex;
         }
 
@@ -90,7 +90,7 @@ IceInternal::TcpEndpointI::TcpEndpointI(const InstancePtr& instance, const strin
                 if(argument.empty())
                 {
                     EndpointParseException ex(__FILE__, __LINE__);
-                    ex.str = "tcp " + str;
+                    ex.str = "no argument provided for -h option in endpoint `tcp " + str + "'";
                     throw ex;
                 }
                 const_cast<string&>(_host) = argument;
@@ -99,11 +99,23 @@ IceInternal::TcpEndpointI::TcpEndpointI(const InstancePtr& instance, const strin
 
             case 'p':
             {
+                if(argument.empty())
+                {
+                    EndpointParseException ex(__FILE__, __LINE__);
+                    ex.str = "no argument provided for -p option in endpoint `tcp " + str + "'";
+                    throw ex;
+                }
                 istringstream p(argument);
-                if(!(p >> const_cast<Int&>(_port)) || !p.eof() || _port < 0 || _port > 65535)
+                if(!(p >> const_cast<Int&>(_port)) || !p.eof())
+                {
+                    EndpointParseException ex(__FILE__, __LINE__);
+                    ex.str = "invalid port value `" + argument + "' in endpoint `tcp " + str + "'";
+                    throw ex;
+                }
+                else if(_port < 0 || _port > 65535)
                 {
                     EndpointParseException ex(__FILE__, __LINE__);
-                    ex.str = "tcp " + str;
+                    ex.str = "port value `" + argument + "' out of range in endpoint `tcp " + str + "'";
                     throw ex;
                 }
                 break;
@@ -111,11 +123,17 @@ IceInternal::TcpEndpointI::TcpEndpointI(const InstancePtr& instance, const strin
 
             case 't':
             {
+                if(argument.empty())
+                {
+                    EndpointParseException ex(__FILE__, __LINE__);
+                    ex.str = "no argument provided for -t option in endpoint `tcp " + str + "'";
+                    throw ex;
+                }
                 istringstream t(argument);
                 if(!(t >> const_cast<Int&>(_timeout)) || !t.eof())
                 {
                     EndpointParseException ex(__FILE__, __LINE__);
-                    ex.str = "tcp " + str;
+                    ex.str = "invalid timeout value `" + argument + "' in endpoint `tcp " + str + "'";
                     throw ex;
                 }
                 break;
@@ -126,7 +144,7 @@ IceInternal::TcpEndpointI::TcpEndpointI(const InstancePtr& instance, const strin
                 if(!argument.empty())
                 {
                     EndpointParseException ex(__FILE__, __LINE__);
-                    ex.str = "tcp " + str;
+                    ex.str = "unexpected argument `" + argument + "' provided for -z option in `tcp " + str + "'";
                     throw ex;
                 }
                 const_cast<bool&>(_compress) = true;
@@ -136,7 +154,7 @@ IceInternal::TcpEndpointI::TcpEndpointI(const InstancePtr& instance, const strin
             default:
             {
                 EndpointParseException ex(__FILE__, __LINE__);
-                ex.str = "tcp " + str;
+                ex.str = "unknown option `" + option + "' in `tcp " + str + "'";
                 throw ex;
             }
         }
@@ -155,7 +173,7 @@ IceInternal::TcpEndpointI::TcpEndpointI(const InstancePtr& instance, const strin
         else
         {
             EndpointParseException ex(__FILE__, __LINE__);
-            ex.str = "tcp " + str;
+            ex.str = "`-h *' not valid for proxy endpoint `tcp " + str + "'";
             throw ex;
         }
     }
diff --git a/cpp/src/Ice/UdpEndpointI.cpp b/cpp/src/Ice/UdpEndpointI.cpp
index 6d0ed5e6989..9119ece31f9 100644
--- a/cpp/src/Ice/UdpEndpointI.cpp
+++ b/cpp/src/Ice/UdpEndpointI.cpp
@@ -74,7 +74,7 @@ IceInternal::UdpEndpointI::UdpEndpointI(const InstancePtr& instance, const strin
         if(option[0] != '-')
         {
             EndpointParseException ex(__FILE__, __LINE__);
-            ex.str = "udp " + str;
+            ex.str = "expected an endpoint option but found `" + option + "' in endpoint `udp " + str + "'";
             throw ex;
         }
 
@@ -89,7 +89,7 @@ IceInternal::UdpEndpointI::UdpEndpointI(const InstancePtr& instance, const strin
                 if(end == string::npos)
                 {
                     EndpointParseException ex(__FILE__, __LINE__);
-                    ex.str = "udp " + str;
+                    ex.str = "mismatched quotes around `" + argument + "' in endpoint `udp " + str + "'";
                     throw ex;
                 }
                 else
@@ -117,7 +117,7 @@ IceInternal::UdpEndpointI::UdpEndpointI(const InstancePtr& instance, const strin
             if(argument.empty())
             {
                 EndpointParseException ex(__FILE__, __LINE__);
-                ex.str = "udp " + str;
+                ex.str = "no argument provided for -v option in endpoint `udp " + str + "'";
                 throw ex;
             }
 
@@ -125,7 +125,7 @@ IceInternal::UdpEndpointI::UdpEndpointI(const InstancePtr& instance, const strin
             if(pos == string::npos)
             {
                 EndpointParseException ex(__FILE__, __LINE__);
-                ex.str = "udp " + str;
+                ex.str = "malformed protocol version `" + argument + "' in endpoint `udp " + str + "'";
                 throw ex;
             }
             string majorStr = argument.substr(0, pos);
@@ -136,7 +136,7 @@ IceInternal::UdpEndpointI::UdpEndpointI(const InstancePtr& instance, const strin
             if(!(majStr >> majVersion) || !majStr.eof())
             {
                 EndpointParseException ex(__FILE__, __LINE__);
-                ex.str = "udp " + str;
+                ex.str = "invalid protocol major version `" + argument + "' in endpoint `udp " + str + "'";
                 throw ex;
             }
 
@@ -145,14 +145,14 @@ IceInternal::UdpEndpointI::UdpEndpointI(const InstancePtr& instance, const strin
             if(!(minStr >> minVersion) || !minStr.eof())
             {
                 EndpointParseException ex(__FILE__, __LINE__);
-                ex.str = "udp " + str;
+                ex.str = "invalid protocol minor version `" + argument + "' in endpoint `udp " + str + "'";
                 throw ex;
             }
 
             if(majVersion < 1 || majVersion > 255 || minVersion < 0 || minVersion > 255)
             {
                 EndpointParseException ex(__FILE__, __LINE__);
-                ex.str = "udp " + str;
+                ex.str = "range error in protocol version `" + argument + "' in endpoint `udp " + str + "'";
                 throw ex;
             }
 
@@ -174,7 +174,7 @@ IceInternal::UdpEndpointI::UdpEndpointI(const InstancePtr& instance, const strin
             if(argument.empty())
             {
                 EndpointParseException ex(__FILE__, __LINE__);
-                ex.str = "udp " + str;
+                ex.str = "no argument provided for -e option in endpoint `udp " + str + "'";
                 throw ex;
             }
             string::size_type pos = argument.find('.');
@@ -186,7 +186,7 @@ IceInternal::UdpEndpointI::UdpEndpointI(const InstancePtr& instance, const strin
             if(!(majStr >> majVersion) || !majStr.eof())
             {
                 EndpointParseException ex(__FILE__, __LINE__);
-                ex.str = "udp " + str;
+                ex.str = "invalid encoding major version `" + argument + "' in endpoint `udp " + str + "'";
                 throw ex;
             }
 
@@ -195,14 +195,14 @@ IceInternal::UdpEndpointI::UdpEndpointI(const InstancePtr& instance, const strin
             if(!(minStr >> minVersion) || !minStr.eof())
             {
                 EndpointParseException ex(__FILE__, __LINE__);
-                ex.str = "udp " + str;
+                ex.str = "invalid encoding minor version `" + argument + "' in endpoint `udp " + str + "'";
                 throw ex;
             }
 
             if(majVersion < 1 || majVersion > 255 || minVersion < 0 || minVersion > 255)
             {
                 EndpointParseException ex(__FILE__, __LINE__);
-                ex.str = "udp " + str;
+                ex.str = "range error in encoding version `" + argument + "' in endpoint `udp " + str + "'";
                 throw ex;
             }
 
@@ -224,18 +224,30 @@ IceInternal::UdpEndpointI::UdpEndpointI(const InstancePtr& instance, const strin
             if(argument.empty())
             {
                 EndpointParseException ex(__FILE__, __LINE__);
-                ex.str = "udp " + str;
+                ex.str = "no argument provided for -h option in endpoint `udp " + str + "'";
                 throw ex;
             }
             const_cast<string&>(_host) = argument;
         }
         else if(option == "-p")
         {
+            if(argument.empty())
+            {
+                EndpointParseException ex(__FILE__, __LINE__);
+                ex.str = "no argument provided for -p option in endpoint `udp " + str + "'";
+                throw ex;
+            }
             istringstream p(argument);
-            if(!(p >> const_cast<Int&>(_port)) || !p.eof() || _port < 0 || _port > 65535)
+            if(!(p >> const_cast<Int&>(_port)) || !p.eof())
+            {
+                EndpointParseException ex(__FILE__, __LINE__);
+                ex.str = "invalid port value `" + argument + "' in endpoint `udp " + str + "'";
+                throw ex;
+            }
+            else if(_port < 0 || _port > 65535)
             {
                 EndpointParseException ex(__FILE__, __LINE__);
-                ex.str = "udp " + str;
+                ex.str = "port value `" + argument + "' out of range in endpoint `udp " + str + "'";
                 throw ex;
             }
         }
@@ -244,7 +256,7 @@ IceInternal::UdpEndpointI::UdpEndpointI(const InstancePtr& instance, const strin
             if(!argument.empty())
             {
                 EndpointParseException ex(__FILE__, __LINE__);
-                ex.str = "udp " + str;
+                ex.str = "unexpected argument `" + argument + "' provided for -c option in `udp " + str + "'";
                 throw ex;
             }
             const_cast<bool&>(_connect) = true;
@@ -254,7 +266,7 @@ IceInternal::UdpEndpointI::UdpEndpointI(const InstancePtr& instance, const strin
             if(!argument.empty())
             {
                 EndpointParseException ex(__FILE__, __LINE__);
-                ex.str = "udp " + str;
+                ex.str = "unexpected argument `" + argument + "' provided for -z option in `udp " + str + "'";
                 throw ex;
             }
             const_cast<bool&>(_compress) = true;
@@ -264,25 +276,31 @@ IceInternal::UdpEndpointI::UdpEndpointI(const InstancePtr& instance, const strin
             if(argument.empty())
             {
                 EndpointParseException ex(__FILE__, __LINE__);
-                ex.str = "udp " + str;
+                ex.str = "no argument provided for --interface option in endpoint `udp " + str + "'";
                 throw ex;
             }
             const_cast<string&>(_mcastInterface) = argument;
         }
         else if(option == "--ttl")
         {
+            if(argument.empty())
+            {
+                EndpointParseException ex(__FILE__, __LINE__);
+                ex.str = "no argument provided for --ttl option in endpoint `udp " + str + "'";
+                throw ex;
+            }
             istringstream p(argument);
             if(!(p >> const_cast<Int&>(_mcastTtl)) || !p.eof())
             {
                 EndpointParseException ex(__FILE__, __LINE__);
-                ex.str = "udp " + str;
+                ex.str = "invalid TTL value `" + argument + "' in endpoint `udp " + str + "'";
                 throw ex;
             }
         }
         else
         {
             EndpointParseException ex(__FILE__, __LINE__);
-            ex.str = "udp " + str;
+            ex.str = "unknown option `" + option + "' in `udp " + str + "'";
             throw ex;
         }
     }
@@ -300,7 +318,7 @@ IceInternal::UdpEndpointI::UdpEndpointI(const InstancePtr& instance, const strin
         else
         {
             EndpointParseException ex(__FILE__, __LINE__);
-            ex.str = "udp " + str;
+            ex.str = "`-h *' not valid for proxy endpoint `udp " + str + "'";
             throw ex;
         }
     }
diff --git a/cpp/src/IcePatch2Lib/Util.cpp b/cpp/src/IcePatch2Lib/Util.cpp
index 0aeb63fbbf6..0d73f1df4c4 100644
--- a/cpp/src/IcePatch2Lib/Util.cpp
+++ b/cpp/src/IcePatch2Lib/Util.cpp
@@ -150,7 +150,14 @@ IcePatch2::readFileInfo(FILE* fp, FileInfo& info)
 
     string s;
     getline(is, s, '\t');
-    IceUtilInternal::unescapeString(s, 0, s.size(), info.path);
+    try
+    {
+        info.path = IceUtilInternal::unescapeString(s, 0, s.size());
+    }
+    catch(const IceUtil::IllegalArgumentException& ex)
+    {
+        throw ex.reason();
+    }
 
     getline(is, s, '\t');
     info.checksum = stringToBytes(s);
diff --git a/cpp/src/IceSSL/EndpointI.cpp b/cpp/src/IceSSL/EndpointI.cpp
index 01e32c9c47a..d1b699d4859 100644
--- a/cpp/src/IceSSL/EndpointI.cpp
+++ b/cpp/src/IceSSL/EndpointI.cpp
@@ -62,7 +62,7 @@ IceSSL::EndpointI::EndpointI(const InstancePtr& instance, const string& str, boo
         if(option.length() != 2 || option[0] != '-')
         {
             EndpointParseException ex(__FILE__, __LINE__);
-            ex.str = "ssl " + str;
+            ex.str = "expected an endpoint option but found `" + option + "' in endpoint `ssl " + str + "'";
             throw ex;
         }
 
@@ -90,7 +90,7 @@ IceSSL::EndpointI::EndpointI(const InstancePtr& instance, const string& str, boo
                 if(argument.empty())
                 {
                     EndpointParseException ex(__FILE__, __LINE__);
-                    ex.str = "ssl " + str;
+                    ex.str = "no argument provided for -h option in endpoint `ssl " + str + "'";
                     throw ex;
                 }
                 const_cast<string&>(_host) = argument;
@@ -99,11 +99,23 @@ IceSSL::EndpointI::EndpointI(const InstancePtr& instance, const string& str, boo
 
             case 'p':
             {
+                if(argument.empty())
+                {
+                    EndpointParseException ex(__FILE__, __LINE__);
+                    ex.str = "no argument provided for -p option in endpoint `ssl " + str + "'";
+                    throw ex;
+                }
                 istringstream p(argument);
-                if(!(p >> const_cast<Int&>(_port)) || !p.eof() || _port < 0 || _port > 65535)
+                if(!(p >> const_cast<Int&>(_port)) || !p.eof())
+                {
+                    EndpointParseException ex(__FILE__, __LINE__);
+                    ex.str = "invalid port value `" + argument + "' in endpoint `ssl " + str + "'";
+                    throw ex;
+                }
+                else if(_port < 0 || _port > 65535)
                 {
                     EndpointParseException ex(__FILE__, __LINE__);
-                    ex.str = "ssl " + str;
+                    ex.str = "port value `" + argument + "' out of range in endpoint `ssl " + str + "'";
                     throw ex;
                 }
                 break;
@@ -111,11 +123,17 @@ IceSSL::EndpointI::EndpointI(const InstancePtr& instance, const string& str, boo
 
             case 't':
             {
+                if(argument.empty())
+                {
+                    EndpointParseException ex(__FILE__, __LINE__);
+                    ex.str = "no argument provided for -t option in endpoint `ssl " + str + "'";
+                    throw ex;
+                }
                 istringstream t(argument);
                 if(!(t >> const_cast<Int&>(_timeout)) || !t.eof())
                 {
                     EndpointParseException ex(__FILE__, __LINE__);
-                    ex.str = "ssl " + str;
+                    ex.str = "invalid timeout value `" + argument + "' in endpoint `ssl " + str + "'";
                     throw ex;
                 }
                 break;
@@ -126,7 +144,7 @@ IceSSL::EndpointI::EndpointI(const InstancePtr& instance, const string& str, boo
                 if(!argument.empty())
                 {
                     EndpointParseException ex(__FILE__, __LINE__);
-                    ex.str = "ssl " + str;
+                    ex.str = "unexpected argument `" + argument + "' provided for -z option in `ssl " + str + "'";
                     throw ex;
                 }
                 const_cast<bool&>(_compress) = true;
@@ -136,7 +154,7 @@ IceSSL::EndpointI::EndpointI(const InstancePtr& instance, const string& str, boo
             default:
             {
                 EndpointParseException ex(__FILE__, __LINE__);
-                ex.str = "ssl " + str;
+                ex.str = "unknown option `" + option + "' in `ssl " + str + "'";
                 throw ex;
             }
         }
@@ -155,7 +173,7 @@ IceSSL::EndpointI::EndpointI(const InstancePtr& instance, const string& str, boo
         else
         {
             EndpointParseException ex(__FILE__, __LINE__);
-            ex.str = "ssl " + str;
+            ex.str = "`-h *' not valid for proxy endpoint `ssl " + str + "'";
             throw ex;
         }
     }
diff --git a/cpp/src/IceUtil/StringUtil.cpp b/cpp/src/IceUtil/StringUtil.cpp
index 3c65ad42dd7..296c5dd9cf6 100644
--- a/cpp/src/IceUtil/StringUtil.cpp
+++ b/cpp/src/IceUtil/StringUtil.cpp
@@ -161,11 +161,22 @@ namespace
 {
 
 char
-checkChar(char c)
+checkChar(const string& s, string::size_type pos)
 {
-    if(!(static_cast<unsigned char>(c) >= 32 && static_cast<unsigned char>(c) <= 126))
+    unsigned char c = static_cast<unsigned char>(s[pos]);
+    if(!(c >= 32 && c <= 126))
     {
-        throw IllegalArgumentException(__FILE__, __LINE__, "illegal input character");
+        ostringstream ostr;
+        if(pos > 0)
+        {
+            ostr << "character after `" << s.substr(0, pos) << "'";
+        }
+        else
+        {
+            ostr << "first character";
+        }
+        ostr << " is not a printable ASCII character (ordinal " << (int)c << ")";
+        throw IllegalArgumentException(__FILE__, __LINE__, ostr.str());
     }
     return c;
 }
@@ -186,13 +197,13 @@ decodeChar(const string& s, string::size_type start, string::size_type end, stri
 
     if(s[start] != '\\')
     {
-        c = checkChar(s[start++]);
+        c = checkChar(s, start++);
     }
     else
     {
         if(start + 1 == end)
         {
-            throw IllegalArgumentException(__FILE__, __LINE__, "trailing backslash in argument");
+            throw IllegalArgumentException(__FILE__, __LINE__, "trailing backslash");
         }
         switch(s[++start])
         {
@@ -242,7 +253,7 @@ decodeChar(const string& s, string::size_type start, string::size_type end, stri
             case '6':
             case '7':
             {
-                int oct = 0;
+                int val = 0;
                 for(int j = 0; j < 3 && start < end; ++j)
                 {
                     int charVal = s[start++] - '0';
@@ -251,18 +262,20 @@ decodeChar(const string& s, string::size_type start, string::size_type end, stri
                         --start;
                         break;
                     }
-                    oct = oct * 8 + charVal;
+                    val = val * 8 + charVal;
                 }
-                if(oct > 255)
+                if(val > 255)
                 {
-                    throw IllegalArgumentException(__FILE__, __LINE__, "octal value out of range");
+                    ostringstream ostr;
+                    ostr << "octal value \\" << oct << val << dec << " (" << val << ") is out of range";
+                    throw IllegalArgumentException(__FILE__, __LINE__, ostr.str());
                 }
-                c = (char)oct;
+                c = (char)val;
                 break;
             }
             default:
             {
-                c = checkChar(s[start++]);
+                c = checkChar(s, start++);
                 break;
             }
         }
@@ -289,30 +302,16 @@ decodeString(const string& s, string::size_type start, string::size_type end, st
 //
 // Remove escape sequences added by escapeString.
 //
-bool
-IceUtilInternal::unescapeString(const string& s, string::size_type start, string::size_type end, string& result)
+string
+IceUtilInternal::unescapeString(const string& s, string::size_type start, string::size_type end)
 {
-    if(end > s.size())
-    {
-        throw IllegalArgumentException(__FILE__, __LINE__, "end offset must be <= s.size()");
-    }
-    if(start > end)
-    {
-        throw IllegalArgumentException(__FILE__, __LINE__, "start offset must <= end offset");
-    }
+    assert(start <= end && end <= s.size());
 
+    string result;
     result.reserve(end - start);
-
-    try
-    {
-        result.clear();
-        decodeString(s, start, end, result);
-        return true;
-    }
-    catch(...)
-    {
-        return false;
-    }
+    result.clear();
+    decodeString(s, start, end, result);
+    return result;
 }
 
 bool
diff --git a/cpp/test/Ice/proxy/AllTests.cpp b/cpp/test/Ice/proxy/AllTests.cpp
index 7165938a046..271f849d39a 100644
--- a/cpp/test/Ice/proxy/AllTests.cpp
+++ b/cpp/test/Ice/proxy/AllTests.cpp
@@ -93,6 +93,27 @@ allTests(const Ice::CommunicatorPtr& communicator)
     test(b1->ice_getIdentity().name == "test" && b1->ice_getIdentity().category == "category" &&
          b1->ice_getAdapterId().empty());
 
+    b1 = communicator->stringToProxy("");
+    test(!b1);
+    b1 = communicator->stringToProxy("\"\"");
+    test(!b1);
+    try
+    {
+        b1 = communicator->stringToProxy("\"\" test"); // Invalid trailing characters.
+        test(false);
+    }
+    catch(const Ice::ProxyParseException&)
+    {
+    }
+    try
+    {
+        b1 = communicator->stringToProxy("test:"); // Missing endpoint.
+        test(false);
+    }
+    catch(const Ice::EndpointParseException&)
+    {
+    }
+
     b1 = communicator->stringToProxy("test@adapter");
     test(b1->ice_getIdentity().name == "test" && b1->ice_getIdentity().category.empty() &&
          b1->ice_getAdapterId() == "adapter");
diff --git a/cs/src/Ice/DefaultsAndOverrides.cs b/cs/src/Ice/DefaultsAndOverrides.cs
index a74c4746e78..a5555a34a64 100644
--- a/cs/src/Ice/DefaultsAndOverrides.cs
+++ b/cs/src/Ice/DefaultsAndOverrides.cs
@@ -111,7 +111,7 @@ namespace IceInternal
             else
             {
                 Ice.EndpointSelectionTypeParseException ex = new Ice.EndpointSelectionTypeParseException();
-                ex.str = val;
+                ex.str = "illegal value `" + val + "'; expected `Random' or `Ordered'";
                 throw ex;
             }
 
diff --git a/cs/src/Ice/EndpointFactoryManager.cs b/cs/src/Ice/EndpointFactoryManager.cs
index b91266d6b0a..db4b350a6e5 100644
--- a/cs/src/Ice/EndpointFactoryManager.cs
+++ b/cs/src/Ice/EndpointFactoryManager.cs
@@ -62,7 +62,7 @@ namespace IceInternal
                 if(s.Length == 0)
                 {
                     Ice.EndpointParseException e = new Ice.EndpointParseException();
-                    e.str = str;
+                    e.str = "value has no non-whitespace characters";
                     throw e;
                 }
                 
diff --git a/cs/src/Ice/ObjectAdapterI.cs b/cs/src/Ice/ObjectAdapterI.cs
index b8037bbd199..be95413e19d 100644
--- a/cs/src/Ice/ObjectAdapterI.cs
+++ b/cs/src/Ice/ObjectAdapterI.cs
@@ -1236,7 +1236,7 @@ namespace Ice
                         continue;
                     }
                     Ice.EndpointParseException e2 = new Ice.EndpointParseException();
-                    e2.str = s;
+                    e2.str = "invalid object adapter endpoint `" + s + "'";
                     throw e2;
                 }
                 endpoints.Add(endp);
diff --git a/cs/src/Ice/OpaqueEndpointI.cs b/cs/src/Ice/OpaqueEndpointI.cs
index 7524d14b0e1..e12cb50bca8 100644
--- a/cs/src/Ice/OpaqueEndpointI.cs
+++ b/cs/src/Ice/OpaqueEndpointI.cs
@@ -36,7 +36,8 @@ namespace IceInternal
                 string option = arr[i++];
                 if(option.Length != 2 || option[0] != '-')
                 {
-                    throw new Ice.EndpointParseException("opaque " + str);
+                    throw new Ice.EndpointParseException("expected an endpoint option but found `" + option +
+                                                         "' in endpoint `opaque " + str + "'");
                 }
 
                 string argument = null;
@@ -51,7 +52,8 @@ namespace IceInternal
                     {
                         if(argument == null)
                         {
-                            throw new Ice.EndpointParseException("opaque " + str);
+                            throw new Ice.EndpointParseException(
+                                "no argument provided for -t option in endpoint `opaque " + str + "'");
                         }
 
                         int t;
@@ -61,16 +63,23 @@ namespace IceInternal
                         }
                         catch(System.FormatException)
                         {
-                            throw new Ice.EndpointParseException("opaque " + str);
+                            throw new Ice.EndpointParseException("invalid timeout value `" + argument +
+                                                                 "' in endpoint `opaque " + str + "'");
                         }
 
                         if(t < 0 || t > 65535)
                         {
-                            throw new Ice.EndpointParseException("opaque " + str);
+                            throw new Ice.EndpointParseException("timeout value `" + argument +
+                                                                 "' out of range in endpoint `opaque " + str + "'");
                         }
 
                         _type = (short)t;
                         ++topt;
+                        if(topt > 1)
+                        {
+                            throw new Ice.EndpointParseException("multiple -t options in endpoint `opaque " + str +
+                                                                 "'");
+                        }
                         break;
                     }
 
@@ -78,30 +87,43 @@ namespace IceInternal
                     {
                         if(argument == null)
                         {
-                            throw new Ice.EndpointParseException("opaque " + str);
+                            throw new Ice.EndpointParseException(
+                                "no argument provided for -v option in endpoint `opaque " + str + "'");
                         }
                         for(int j = 0; j < argument.Length; ++j)
                         {
                             if(!IceUtilInternal.Base64.isBase64(argument[j]))
                             {
-                                throw new Ice.EndpointParseException("opaque " + str);
+                                throw new Ice.EndpointParseException(
+                                    "invalid base64 character `" + argument[j] + "' (ordinal " +
+                                    ((int)argument[j]) + ") in endpoint `opaque " + str + "'");
                             }
                         }
                         _rawBytes = IceUtilInternal.Base64.decode(argument);
                         ++vopt;
+                        if(vopt > 1)
+                        {
+                            throw new Ice.EndpointParseException("multiple -v options in endpoint `opaque " + str +
+                                                                 "'");
+                        }
                         break;
                     }
 
                     default:
                     {
-                        throw new Ice.EndpointParseException("opaque " + str);
+                        throw new Ice.EndpointParseException("invalid option `" + option + "' in endpoint `opaque " +
+                                                              str + "'");
                     }
                 }
             }
 
-            if(topt != 1 || vopt != 1)
+            if(topt != 1)
+            {
+                throw new Ice.EndpointParseException("no -t option in endpoint `opaque " + str + "'");
+            }
+            if(vopt != 1)
             {
-                throw new Ice.EndpointParseException("opaque " + str);
+                throw new Ice.EndpointParseException("no -v option in endpoint `opaque " + str + "'");
             }
             calcHashValue();
         }
diff --git a/cs/src/Ice/ReferenceFactory.cs b/cs/src/Ice/ReferenceFactory.cs
index 0c3fa9891c5..3fab0d4c990 100644
--- a/cs/src/Ice/ReferenceFactory.cs
+++ b/cs/src/Ice/ReferenceFactory.cs
@@ -10,6 +10,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Text;
 
 namespace IceInternal
@@ -89,7 +90,7 @@ namespace IceInternal
             if(beg == -1)
             {
                 Ice.ProxyParseException e = new Ice.ProxyParseException();
-                e.str = s;
+                e.str = "no non-whitespace characters found in `" + s + "'";
                 throw e;
             }
 
@@ -102,7 +103,7 @@ namespace IceInternal
             if(end == -1)
             {
                 Ice.ProxyParseException e = new Ice.ProxyParseException();
-                e.str = s;
+                e.str = "mismatched quotes around identity in `" + s + "'";
                 throw e;
             }
             else if(end == 0)
@@ -124,7 +125,7 @@ namespace IceInternal
             if(beg == end)
             {
                 Ice.ProxyParseException e = new Ice.ProxyParseException();
-                e.str = s;
+                e.str = "no identity in `" + s + "'";
                 throw e;
             }
 
@@ -154,7 +155,7 @@ namespace IceInternal
                 else if(IceUtilInternal.StringUtil.findFirstNotOf(s, delim, end) != -1)
                 {
                     Ice.ProxyParseException e = new Ice.ProxyParseException();
-                    e.str = s;
+                    e.str = "invalid characters after identity in `" + s + "'";
                     throw e;
                 }
                 else
@@ -196,7 +197,7 @@ namespace IceInternal
                 if(option.Length != 2 || option[0] != '-')
                 {
                     Ice.ProxyParseException e = new Ice.ProxyParseException();
-                    e.str = s;
+                    e.str = "expected a proxy option but found `" + option + "' in `" + s + "'";
                     throw e;
                 }
 
@@ -217,7 +218,7 @@ namespace IceInternal
                         if(end == -1)
                         {
                             Ice.ProxyParseException e = new Ice.ProxyParseException();
-                            e.str = s;
+                            e.str = "mismatched quotes around value for " + option + " option in `" + s + "'";
                             throw e;
                         }
                         else if(end == 0)
@@ -249,18 +250,20 @@ namespace IceInternal
                         if(argument == null)
                         {
                             Ice.ProxyParseException e = new Ice.ProxyParseException();
-                            e.str = s;
+                            e.str = "no argument provided for -f option in `" + s + "'";
                             throw e;
                         }
 
-                        string token;
-                        if(!IceUtilInternal.StringUtil.unescapeString(argument, 0, argument.Length, out token))
+                        try
+                        {
+                            facet = IceUtilInternal.StringUtil.unescapeString(argument, 0, argument.Length);
+                        }
+                        catch(System.ArgumentException argEx)
                         {
                             Ice.ProxyParseException e = new Ice.ProxyParseException();
-                            e.str = s;
+                            e.str = "invalid facet in `" + s + "': " + argEx.Message;
                             throw e;
                         }
-                        facet = token;
                         break;
                     }
 
@@ -269,7 +272,7 @@ namespace IceInternal
                         if(argument != null)
                         {
                             Ice.ProxyParseException e = new Ice.ProxyParseException();
-                            e.str = s;
+                            e.str = "unexpected argument `" + argument + "' provided for -t option in `" + s + "'";
                             throw e;
                         }
                         mode = Reference.Mode.ModeTwoway;
@@ -281,7 +284,7 @@ namespace IceInternal
                         if(argument != null)
                         {
                             Ice.ProxyParseException e = new Ice.ProxyParseException();
-                            e.str = s;
+                            e.str = "unexpected argument `" + argument + "' provided for -o option in `" + s + "'";
                             throw e;
                         }
                         mode = Reference.Mode.ModeOneway;
@@ -293,7 +296,7 @@ namespace IceInternal
                         if(argument != null)
                         {
                             Ice.ProxyParseException e = new Ice.ProxyParseException();
-                            e.str = s;
+                            e.str = "unexpected argument `" + argument + "' provided for -O option in `" + s + "'";
                             throw e;
                         }
                         mode = Reference.Mode.ModeBatchOneway;
@@ -305,7 +308,7 @@ namespace IceInternal
                         if(argument != null)
                         {
                             Ice.ProxyParseException e = new Ice.ProxyParseException();
-                            e.str = s;
+                            e.str = "unexpected argument `" + argument + "' provided for -d option in `" + s + "'";
                             throw e;
                         }
                         mode = Reference.Mode.ModeDatagram;
@@ -317,7 +320,7 @@ namespace IceInternal
                         if(argument != null)
                         {
                             Ice.ProxyParseException e = new Ice.ProxyParseException();
-                            e.str = s;
+                            e.str = "unexpected argument `" + argument + "' provided for -D option in `" + s + "'";
                             throw e;
                         }
                         mode = Reference.Mode.ModeBatchDatagram;
@@ -329,7 +332,7 @@ namespace IceInternal
                         if(argument != null)
                         {
                             Ice.ProxyParseException e = new Ice.ProxyParseException();
-                            e.str = s;
+                            e.str = "unexpected argument `" + argument + "' provided for -s option in `" + s + "'";
                             throw e;
                         }
                         secure = true;
@@ -339,7 +342,7 @@ namespace IceInternal
                     default:
                     {
                         Ice.ProxyParseException e = new Ice.ProxyParseException();
-                        e.str = s;
+                        e.str = "unknown option `" + option + "' in `" + s + "'";
                         throw e;
                     }
                 }
@@ -417,8 +420,9 @@ namespace IceInternal
                 }
                 if(endpoints.Count == 0)
                 {
+                    Debug.Assert(unknownEndpoints.Count > 0);
                     Ice.EndpointParseException e2 = new Ice.EndpointParseException();
-                    e2.str = s;
+                    e2.str = "invalid endpoint `" + unknownEndpoints[0] + "' in `" + s + "'";
                     throw e2;
                 }
                 else if(unknownEndpoints.Count != 0 &&
@@ -445,7 +449,7 @@ namespace IceInternal
                 if(beg == -1)
                 {
                     Ice.ProxyParseException e = new Ice.ProxyParseException();
-                    e.str = s;
+                    e.str = "missing adapter id in `" + s + "'";
                     throw e;
                 }
 
@@ -454,7 +458,7 @@ namespace IceInternal
                 if(end == -1)
                 {
                     Ice.ProxyParseException e = new Ice.ProxyParseException();
-                    e.str = s;
+                    e.str = "mismatched quotes around adapter id in `" + s + "'";
                     throw e;
                 }
                 else if(end == 0)
@@ -476,22 +480,31 @@ namespace IceInternal
                 if(end != s.Length && IceUtilInternal.StringUtil.findFirstNotOf(s, delim, end) != -1)
                 {
                     Ice.ProxyParseException e = new Ice.ProxyParseException();
-                    e.str = s;
+                    e.str = "invalid trailing characters after `" + s.Substring(0, end + 1) + "' in `" + s + "'";
                     throw e;
                 }
 
-                if(!IceUtilInternal.StringUtil.unescapeString(adapterstr, 0, adapterstr.Length, out adapter) ||
-                   adapter.Length == 0)
+                try
+                {
+                    adapter = IceUtilInternal.StringUtil.unescapeString(adapterstr, 0, adapterstr.Length);
+                }
+                catch(System.ArgumentException argEx)
+                {
+                    Ice.ProxyParseException e = new Ice.ProxyParseException();
+                    e.str = "invalid adapter id in `" + s + "': " + argEx.Message;
+                    throw e;
+                }
+                if(adapter.Length == 0)
                 {
                     Ice.ProxyParseException e = new Ice.ProxyParseException();
-                    e.str = s;
+                    e.str = "empty adapter id in `" + s + "'";
                     throw e;
                 }
                 return create(ident, facet, mode, secure, null, adapter, propertyPrefix);
             }
 
             Ice.ProxyParseException ex = new Ice.ProxyParseException();
-            ex.str = s;
+            ex.str = "malformed proxy `" + s + "'";
             throw ex;
         }
 
@@ -774,7 +787,8 @@ namespace IceInternal
                     }
                     else
                     {
-                        throw new Ice.EndpointSelectionTypeParseException(type);
+                        throw new Ice.EndpointSelectionTypeParseException("illegal value `" + type +
+                                                                          "'; expected `Random' or `Ordered'");
                     }
                 }
         
diff --git a/cs/src/Ice/StringUtil.cs b/cs/src/Ice/StringUtil.cs
index dd5c1d584ca..9db9c17c697 100644
--- a/cs/src/Ice/StringUtil.cs
+++ b/cs/src/Ice/StringUtil.cs
@@ -180,7 +180,8 @@ namespace IceUtilInternal
                 {
                     if((int)special[i] < 32 || (int)special[i] > 126)
                     {
-                        throw new System.ArgumentException("special characters must be in ASCII range 32-126", "special");
+                        throw new System.ArgumentException("special characters must be in ASCII range 32-126",
+                                                           "special");
                     }
                 }
             }
@@ -197,11 +198,22 @@ namespace IceUtilInternal
             return result.ToString();
         }
         
-        private static char checkChar(char c)
+        private static char checkChar(string s, int pos)
         {
+            char c = s[pos];
             if(!(c >= 32 && c <= 126))
             {
-                throw new System.ArgumentException("illegal input character");
+                string msg;
+                if(pos > 0)
+                {
+                    msg = "character after `" + s.Substring(0, pos) + "'";
+                }
+                else
+                {
+                    msg = "first character";
+                }
+                msg += " is not a printable ASCII character (ordinal " + (int)c + ")";
+                throw new System.ArgumentException(msg);
             }
             return c;
         }
@@ -222,13 +234,13 @@ namespace IceUtilInternal
 
             if(s[start] != '\\')
             {
-                c = checkChar(s[start++]);
+                c = checkChar(s, start++);
             }
             else
             {
                 if(start + 1 == end)
                 {
-                    throw new System.ArgumentException("trailing backslash in argument");
+                    throw new System.ArgumentException("trailing backslash");
                 }
                 switch(s[++start])
                 {
@@ -278,7 +290,7 @@ namespace IceUtilInternal
                     case '6':
                     case '7':
                     {
-                        int oct = 0;
+                        int val = 0;
                         for(int j = 0; j < 3 && start < end; ++j)
                         {
                             int charVal = s[start++] - '0';
@@ -287,18 +299,20 @@ namespace IceUtilInternal
                                 --start;
                                 break;
                             }
-                            oct = oct * 8 + charVal;
+                            val = val * 8 + charVal;
                         }
-                        if(oct > 255)
+                        if(val > 255)
                         {
-                            throw new System.ArgumentException("octal value out of range", "s");
+                            string msg = "octal value \\" + System.Convert.ToString(val, 8) + " (" + val +
+                                ") is out of range";
+                            throw new System.ArgumentException(msg, "s");
                         }
-                        c = System.Convert.ToChar(oct);
+                        c = System.Convert.ToChar(val);
                         break;
                     }
                     default:
                     {
-                        c = checkChar(s[start++]);
+                        c = checkChar(s, start++);
                         break;
                     }
                 }
@@ -320,44 +334,25 @@ namespace IceUtilInternal
         }
 
         //
-        // Remove escape sequences added by escapeString.
+        // Remove escape sequences added by escapeString. Throws System.ArgumentException
+        // for an invalid input string.
         //
-        public static bool unescapeString(string s, int start, int end, out string result)
+        public static string unescapeString(string s, int start, int end)
         {
-            if(start < 0)
-            {
-                throw new System.ArgumentException("start offset must be >= 0", "start");
-            }
-            if(end > s.Length)
-            {
-                throw new System.ArgumentException("end offset must be <= s.Length", "end");
-            }
-            if(start > end)
-            {
-                throw new System.ArgumentException("start offset must be <= end offset");
-            }
-            
-            result = null;
-            try
-            {
-                StringBuilder sb = new StringBuilder();
-                decodeString(s, start, end, sb);
-                string decodedString = sb.ToString();
+            Debug.Assert(start >= 0 && start <= end && end <= s.Length);
 
-                byte[] arr = new byte[decodedString.Length];
-                for(int i = 0; i < arr.Length; ++i)
-                {
-                    arr[i] = (byte)decodedString[i];
-                }
+            StringBuilder sb = new StringBuilder();
+            decodeString(s, start, end, sb);
+            string decodedString = sb.ToString();
 
-                UTF8Encoding utf8 = new UTF8Encoding(false, true);
-                result = utf8.GetString(arr);
-                return true;
-            }
-            catch(System.Exception)
+            byte[] arr = new byte[decodedString.Length];
+            for(int i = 0; i < arr.Length; ++i)
             {
-                return false;
+                arr[i] = (byte)decodedString[i];
             }
+
+            UTF8Encoding utf8 = new UTF8Encoding(false, true);
+            return utf8.GetString(arr); // May raise ArgumentException.
         }
 
         public static int checkQuote(string s)
diff --git a/cs/src/Ice/TcpEndpointI.cs b/cs/src/Ice/TcpEndpointI.cs
index 2202d4e3849..b7724d49d7b 100644
--- a/cs/src/Ice/TcpEndpointI.cs
+++ b/cs/src/Ice/TcpEndpointI.cs
@@ -52,7 +52,7 @@ namespace IceInternal
                 if(option.Length != 2 || option[0] != '-')
                 {
                     Ice.EndpointParseException e = new Ice.EndpointParseException();
-                    e.str = "tcp " + str;
+                    e.str = "expected an endpoint option but found `" + option + "' in endpoint `tcp " + str + "'";
                     throw e;
                 }
 
@@ -73,7 +73,7 @@ namespace IceInternal
                         if(argument == null)
                         {
                             Ice.EndpointParseException e = new Ice.EndpointParseException();
-                            e.str = "tcp " + str;
+                            e.str = "no argument provided for -h option in endpoint `tcp " + str + "'";
                             throw e;
                         }
 
@@ -86,7 +86,7 @@ namespace IceInternal
                         if(argument == null)
                         {
                             Ice.EndpointParseException e = new Ice.EndpointParseException();
-                            e.str = "tcp " + str;
+                            e.str = "no argument provided for -p option in endpoint `tcp " + str + "'";
                             throw e;
                         }
 
@@ -97,14 +97,14 @@ namespace IceInternal
                         catch(System.FormatException ex)
                         {
                             Ice.EndpointParseException e = new Ice.EndpointParseException(ex);
-                            e.str = "tcp " + str;
+                            e.str = "invalid port value `" + argument + "' in endpoint `tcp " + str + "'";
                             throw e;
                         }
 
                         if(_port < 0 || _port > 65535)
                         {
                             Ice.EndpointParseException e = new Ice.EndpointParseException();
-                            e.str = "tcp " + str;
+                            e.str = "port value `" + argument + "' out of range in endpoint `tcp " + str + "'";
                             throw e;
                         }
 
@@ -116,7 +116,7 @@ namespace IceInternal
                         if(argument == null)
                         {
                             Ice.EndpointParseException e = new Ice.EndpointParseException();
-                            e.str = "tcp " + str;
+                            e.str = "no argument provided for -t option in endpoint `tcp " + str + "'";
                             throw e;
                         }
 
@@ -127,7 +127,7 @@ namespace IceInternal
                         catch(System.FormatException ex)
                         {
                             Ice.EndpointParseException e = new Ice.EndpointParseException(ex);
-                            e.str = "tcp " + str;
+                            e.str = "invalid timeout value `" + argument + "' in endpoint `tcp " + str + "'";
                             throw e;
                         }
 
@@ -139,7 +139,8 @@ namespace IceInternal
                         if(argument != null)
                         {
                             Ice.EndpointParseException e = new Ice.EndpointParseException();
-                            e.str = "tcp " + str;
+                            e.str = "unexpected argument `" + argument + "' provided for -z option in `tcp " + str +
+                                    "'";
                             throw e;
                         }
 
@@ -150,7 +151,7 @@ namespace IceInternal
                     default:
                     {
                         Ice.EndpointParseException e = new Ice.EndpointParseException();
-                        e.str = "tcp " + str;
+                        e.str = "unknown option `" + option + "' in `tcp " + str + "'";
                         throw e;
                     }
                 }
@@ -168,7 +169,7 @@ namespace IceInternal
                 }
                 else
                 {
-                    throw new Ice.EndpointParseException("tcp " + str);
+                    throw new Ice.EndpointParseException("`-h *' not valid for proxy endpoint `tcp " + str + "'");
                 }
             }
 
diff --git a/cs/src/Ice/UdpEndpointI.cs b/cs/src/Ice/UdpEndpointI.cs
index 0ed3b07af48..538d0564fa9 100644
--- a/cs/src/Ice/UdpEndpointI.cs
+++ b/cs/src/Ice/UdpEndpointI.cs
@@ -72,7 +72,7 @@ namespace IceInternal
                 if(option[0] != '-')
                 {
                     Ice.EndpointParseException e = new Ice.EndpointParseException();
-                    e.str = "udp " + str;
+                    e.str = "expected an endpoint option but found `" + option + "' in endpoint `udp " + str + "'";
                     throw e;
                 }
 
@@ -87,7 +87,7 @@ namespace IceInternal
                         if(end == -1)
                         {
                             Ice.EndpointParseException e = new Ice.EndpointParseException();
-                            e.str = "udp " + str;
+                            e.str = "mismatched quotes around `" + argument + "' in endpoint `udp " + str + "'";
                             throw e;
                         }
                         else
@@ -115,7 +115,7 @@ namespace IceInternal
                     if(argument == null)
                     {
                         Ice.EndpointParseException e = new Ice.EndpointParseException();
-                        e.str = "udp " + str;
+                        e.str = "no argument provided for -v option in endpoint `udp " + str + "'";
                         throw e;
                     }
                     
@@ -123,7 +123,7 @@ namespace IceInternal
                     if(pos == -1)
                     {
                         Ice.EndpointParseException e = new Ice.EndpointParseException();
-                        e.str = "udp " + str;
+                        e.str = "malformed protocol version `" + argument + "' in endpoint `udp " + str + "'";
                         throw e;
                     }
                     
@@ -139,14 +139,14 @@ namespace IceInternal
                     catch(System.FormatException ex)
                     {
                         Ice.EndpointParseException e = new Ice.EndpointParseException(ex);
-                        e.str = "udp " + str;
+                        e.str = "invalid protocol version `" + argument + "' in endpoint `udp " + str + "'";
                         throw e;
                     }
                     
                     if(majVersion < 1 || majVersion > 255 || minVersion < 0 || minVersion > 255)
                     {
                         Ice.EndpointParseException e = new Ice.EndpointParseException();
-                        e.str = "udp " + str;
+                        e.str = "range error in protocol version `" + argument + "' in endpoint `udp " + str + "'";
                         throw e;
                     }
                     
@@ -168,7 +168,7 @@ namespace IceInternal
                     if(argument == null)
                     {
                         Ice.EndpointParseException e = new Ice.EndpointParseException();
-                        e.str = "udp " + str;
+                        e.str = "no argument provided for -e option in endpoint `udp " + str + "'";
                         throw e;
                     }
                 
@@ -176,7 +176,7 @@ namespace IceInternal
                     if(pos == -1)
                     {
                         Ice.EndpointParseException e = new Ice.EndpointParseException();
-                        e.str = "udp " + str;
+                        e.str = "malformed encoding version `" + argument + "' in endpoint `udp " + str + "'";
                         throw e;
                     }
                     
@@ -192,14 +192,14 @@ namespace IceInternal
                     catch(System.FormatException ex)
                     {
                         Ice.EndpointParseException e = new Ice.EndpointParseException(ex);
-                        e.str = "udp " + str;
+                        e.str = "invalid encoding version `" + argument + "' in endpoint `udp " + str + "'";
                         throw e;
                     }
                     
                     if(majVersion < 1 || majVersion > 255 || minVersion < 0 || minVersion > 255)
                     {
                         Ice.EndpointParseException e = new Ice.EndpointParseException();
-                        e.str = "udp " + str;
+                        e.str = "range error in encoding version `" + argument + "' in endpoint `udp " + str + "'";
                         throw e;
                     }
                     
@@ -221,7 +221,7 @@ namespace IceInternal
                     if(argument == null)
                     {
                         Ice.EndpointParseException e = new Ice.EndpointParseException();
-                        e.str = "udp " + str;
+                        e.str = "no argument provided for -h option in endpoint `udp " + str + "'";
                         throw e;
                     }
                     
@@ -232,7 +232,7 @@ namespace IceInternal
                     if(argument == null)
                     {
                         Ice.EndpointParseException e = new Ice.EndpointParseException();
-                        e.str = "udp " + str;
+                        e.str = "no argument provided for -p option in endpoint `udp " + str + "'";
                         throw e;
                     }
                     
@@ -243,14 +243,14 @@ namespace IceInternal
                     catch(System.FormatException ex)
                     {
                         Ice.EndpointParseException e = new Ice.EndpointParseException(ex);
-                        e.str = "udp " + str;
+                        e.str = "invalid port value `" + argument + "' in endpoint `udp " + str + "'";
                         throw e;
                     }
 
                     if(_port < 0 || _port > 65535)
                     {
                         Ice.EndpointParseException e = new Ice.EndpointParseException();
-                        e.str = "udp " + str;
+                        e.str = "port value `" + argument + "' out of range in endpoint `udp " + str + "'";
                         throw e;
                     }
                 }
@@ -259,7 +259,7 @@ namespace IceInternal
                     if(argument != null)
                     {
                         Ice.EndpointParseException e = new Ice.EndpointParseException();
-                        e.str = "udp " + str;
+                        e.str = "unexpected argument `" + argument + "' provided for -c option in `udp " + str + "'";
                         throw e;
                     }
                     
@@ -270,7 +270,7 @@ namespace IceInternal
                     if(argument != null)
                     {
                         Ice.EndpointParseException e = new Ice.EndpointParseException();
-                        e.str = "udp " + str;
+                        e.str = "unexpected argument `" + argument + "' provided for -z option in `udp " + str + "'";
                         throw e;
                     }
                     
@@ -281,7 +281,7 @@ namespace IceInternal
                     if(argument == null)
                     {
                         Ice.EndpointParseException e = new Ice.EndpointParseException();
-                        e.str = "udp " + str;
+                        e.str = "no argument provided for --interface option in endpoint `udp " + str + "'";
                         throw e;
                     }
                     
@@ -292,7 +292,7 @@ namespace IceInternal
                     if(argument == null)
                     {
                         Ice.EndpointParseException e = new Ice.EndpointParseException();
-                        e.str = "udp " + str;
+                        e.str = "no argument provided for --ttl option in endpoint `udp " + str + "'";
                         throw e;
                     }
                     
@@ -303,21 +303,21 @@ namespace IceInternal
                     catch(System.FormatException ex)
                     {
                         Ice.EndpointParseException e = new Ice.EndpointParseException(ex);
-                        e.str = "udp " + str;
+                        e.str = "invalid TTL value `" + argument + "' in endpoint `udp " + str + "'";
                         throw e;
                     }
 
                     if(_mcastTtl < 0)
                     {
                         Ice.EndpointParseException e = new Ice.EndpointParseException();
-                        e.str = "udp " + str;
+                        e.str = "TTL value `" + argument + "' out of range in endpoint `udp " + str + "'";
                         throw e;
                     }
                 }
                 else
                 {
                     Ice.EndpointParseException e = new Ice.EndpointParseException();
-                    e.str = "udp " + str;
+                    e.str = "unknown option `" + option + "' in `udp " + str + "'";
                     throw e;
                 }
             }
@@ -334,7 +334,7 @@ namespace IceInternal
                 }
                 else
                 {
-                    throw new Ice.EndpointParseException("udp " + str);
+                    throw new Ice.EndpointParseException("`-h *' not valid for proxy endpoint `udp " + str + "'");
                 }        
             }
 
diff --git a/cs/src/Ice/Util.cs b/cs/src/Ice/Util.cs
index ff3294f7c14..3367922561b 100644
--- a/cs/src/Ice/Util.cs
+++ b/cs/src/Ice/Util.cs
@@ -226,7 +226,7 @@ namespace Ice
                         // Extra unescaped slash found.
                         //
                         IdentityParseException ex = new IdentityParseException();
-                        ex.str = s;
+                        ex.str = "unescaped backslash in identity `" + s + "'";
                         throw ex;
                     }
                 }
@@ -235,28 +235,40 @@ namespace Ice
 
             if(slash == -1)
             {
-                if(!IceUtilInternal.StringUtil.unescapeString(s, 0, s.Length, out ident.name))
+                ident.category = "";
+                try
+                {
+                    ident.name = IceUtilInternal.StringUtil.unescapeString(s, 0, s.Length);
+                }
+                catch(System.ArgumentException e)
                 {
                     IdentityParseException ex = new IdentityParseException();
-                    ex.str = s;
+                    ex.str = "invalid identity name `" + s + "': " + e.Message;
                     throw ex;
                 }
-                ident.category = "";
             }
             else
             {
-                if(!IceUtilInternal.StringUtil.unescapeString(s, 0, slash, out ident.category))
+                try
+                {
+                    ident.category = IceUtilInternal.StringUtil.unescapeString(s, 0, slash);
+                }
+                catch(System.ArgumentException e)
                 {
                     IdentityParseException ex = new IdentityParseException();
-                    ex.str = s;
+                    ex.str = "invalid category in identity `" + s + "': " + e.Message;
                     throw ex;
                 }
                 if(slash + 1 < s.Length)
                 {
-                    if(!IceUtilInternal.StringUtil.unescapeString(s, slash + 1, s.Length, out ident.name))
+                    try
+                    {
+                        ident.name = IceUtilInternal.StringUtil.unescapeString(s, slash + 1, s.Length);
+                    }
+                    catch(System.ArgumentException e)
                     {
                         IdentityParseException ex = new IdentityParseException();
-                        ex.str = s;
+                        ex.str = "invalid name in identity `" + s + "': " + e.Message;
                         throw ex;
                     }
                 }
diff --git a/cs/src/IceSSL/EndpointI.cs b/cs/src/IceSSL/EndpointI.cs
index 00cb51592fa..9c5eefb552f 100644
--- a/cs/src/IceSSL/EndpointI.cs
+++ b/cs/src/IceSSL/EndpointI.cs
@@ -52,7 +52,7 @@ namespace IceSSL
                 if(option.Length != 2 || option[0] != '-')
                 {
                     Ice.EndpointParseException e = new Ice.EndpointParseException();
-                    e.str = "ssl " + str;
+                    e.str = "expected an endpoint option but found `" + option + "' in endpoint `ssl " + str + "'";
                     throw e;
                 }
 
@@ -73,7 +73,7 @@ namespace IceSSL
                         if(argument == null)
                         {
                             Ice.EndpointParseException e = new Ice.EndpointParseException();
-                            e.str = "ssl " + str;
+                            e.str = "no argument provided for -h option in endpoint `ssl " + str + "'";
                             throw e;
                         }
 
@@ -86,7 +86,7 @@ namespace IceSSL
                         if(argument == null)
                         {
                             Ice.EndpointParseException e = new Ice.EndpointParseException();
-                            e.str = "ssl " + str;
+                            e.str = "no argument provided for -p option in endpoint `ssl " + str + "'";
                             throw e;
                         }
 
@@ -97,14 +97,14 @@ namespace IceSSL
                         catch(System.FormatException ex)
                         {
                             Ice.EndpointParseException e = new Ice.EndpointParseException(ex);
-                            e.str = "ssl " + str;
+                            e.str = "invalid port value `" + argument + "' in endpoint `ssl " + str + "'";
                             throw e;
                         }
 
                         if(_port < 0 || _port > 65535)
                         {
                             Ice.EndpointParseException e = new Ice.EndpointParseException();
-                            e.str = "ssl " + str;
+                            e.str = "port value `" + argument + "' out of range in endpoint `ssl " + str + "'";
                             throw e;
                         }
 
@@ -116,7 +116,7 @@ namespace IceSSL
                         if(argument == null)
                         {
                             Ice.EndpointParseException e = new Ice.EndpointParseException();
-                            e.str = "ssl " + str;
+                            e.str = "no argument provided for -t option in endpoint `ssl " + str + "'";
                             throw e;
                         }
 
@@ -127,7 +127,7 @@ namespace IceSSL
                         catch(System.FormatException ex)
                         {
                             Ice.EndpointParseException e = new Ice.EndpointParseException(ex);
-                            e.str = "ssl " + str;
+                            e.str = "invalid timeout value `" + argument + "' in endpoint `ssl " + str + "'";
                             throw e;
                         }
 
@@ -139,7 +139,8 @@ namespace IceSSL
                         if(argument != null)
                         {
                             Ice.EndpointParseException e = new Ice.EndpointParseException();
-                            e.str = "ssl " + str;
+                            e.str = "unexpected argument `" + argument + "' provided for -z option in `ssl " + str +
+                                    "'";
                             throw e;
                         }
 
@@ -150,7 +151,7 @@ namespace IceSSL
                     default:
                     {
                         Ice.EndpointParseException e = new Ice.EndpointParseException();
-                        e.str = "ssl " + str;
+                        e.str = "unknown option `" + option + "' in `ssl " + str + "'";
                         throw e;
                     }
                 }
@@ -168,7 +169,7 @@ namespace IceSSL
                 }
                 else
                 {
-                    throw new Ice.EndpointParseException("ssl " + str);
+                    throw new Ice.EndpointParseException("`-h *' not valid for proxy endpoint `ssl " + str + "'");
                 }
             }
 
diff --git a/cs/test/Ice/proxy/AllTests.cs b/cs/test/Ice/proxy/AllTests.cs
index dccbb0173c4..3d6c49c22a2 100644
--- a/cs/test/Ice/proxy/AllTests.cs
+++ b/cs/test/Ice/proxy/AllTests.cs
@@ -98,7 +98,28 @@ public class AllTests
         b1 = communicator.stringToProxy("category/test");
         test(b1.ice_getIdentity().name.Equals("test") && b1.ice_getIdentity().category.Equals("category") &&
              b1.ice_getAdapterId().Length == 0);
-             
+
+        b1 = communicator.stringToProxy("");
+        test(b1 == null);
+        b1 = communicator.stringToProxy("\"\"");
+        test(b1 == null);
+        try
+        {
+            b1 = communicator.stringToProxy("\"\" test"); // Invalid trailing characters.
+            test(false);
+        }
+        catch(Ice.ProxyParseException)
+        {
+        }
+        try
+        {
+            b1 = communicator.stringToProxy("test:"); // Missing endpoint.
+            test(false);
+        }
+        catch(Ice.EndpointParseException)
+        {
+        }
+
         b1 = communicator.stringToProxy("test@adapter");
         test(b1.ice_getIdentity().name.Equals("test") && b1.ice_getIdentity().category.Length == 0 &&
              b1.ice_getAdapterId().Equals("adapter"));
diff --git a/java/src/Ice/ObjectAdapterI.java b/java/src/Ice/ObjectAdapterI.java
index b4bd577a414..c0243872304 100644
--- a/java/src/Ice/ObjectAdapterI.java
+++ b/java/src/Ice/ObjectAdapterI.java
@@ -1211,7 +1211,7 @@ public final class ObjectAdapterI implements ObjectAdapter
             if(endp == null)
             {
                 Ice.EndpointParseException e = new Ice.EndpointParseException();
-                e.str = s;
+                e.str = "invalid object adapter endpoint `" + s + "'";
                 throw e;
             }
             endpoints.add(endp);
diff --git a/java/src/Ice/Util.java b/java/src/Ice/Util.java
index dc4253eb627..04ea0dea312 100644
--- a/java/src/Ice/Util.java
+++ b/java/src/Ice/Util.java
@@ -252,7 +252,7 @@ public final class Util
                     // Extra unescaped slash found.
                     //
                     IdentityParseException ex = new IdentityParseException();
-                    ex.str = s;
+                    ex.str = "unescaped backslash in identity `" + s + "'";
                     throw ex;
                 }
             }
@@ -261,35 +261,42 @@ public final class Util
 
         if(slash == -1)
         {
-            StringHolder token = new StringHolder();
-            if(!IceUtilInternal.StringUtil.unescapeString(s, 0, s.length(), token))
+            ident.category = "";
+            try
+            {
+                ident.name = IceUtilInternal.StringUtil.unescapeString(s, 0, s.length());
+            }
+            catch(IllegalArgumentException e)
             {
                 IdentityParseException ex = new IdentityParseException();
-                ex.str = s;
+                ex.str = "invalid identity name `" + s + "': " + e.getMessage();
                 throw ex;
             }
-            ident.category = "";
-            ident.name = token.value;
         }
         else
         {
-            StringHolder token = new StringHolder();
-            if(!IceUtilInternal.StringUtil.unescapeString(s, 0, slash, token))
+            try
+            {
+                ident.category = IceUtilInternal.StringUtil.unescapeString(s, 0, slash);
+            }
+            catch(IllegalArgumentException e)
             {
                 IdentityParseException ex = new IdentityParseException();
-                ex.str = s;
+                ex.str = "invalid category in identity `" + s + "': " + e.getMessage();
                 throw ex;
             }
-            ident.category = token.value;
             if(slash + 1 < s.length())
             {
-                if(!IceUtilInternal.StringUtil.unescapeString(s, slash + 1, s.length(), token))
+                try
+                {
+                    ident.name = IceUtilInternal.StringUtil.unescapeString(s, slash + 1, s.length());
+                }
+                catch(IllegalArgumentException e)
                 {
                     IdentityParseException ex = new IdentityParseException();
-                    ex.str = s;
+                    ex.str = "invalid name in identity `" + s + "': " + e.getMessage();
                     throw ex;
                 }
-                ident.name = token.value;
             }
             else
             {
diff --git a/java/src/IceInternal/DefaultsAndOverrides.java b/java/src/IceInternal/DefaultsAndOverrides.java
index 8946bf6f7b7..ce340c66e1b 100644
--- a/java/src/IceInternal/DefaultsAndOverrides.java
+++ b/java/src/IceInternal/DefaultsAndOverrides.java
@@ -108,7 +108,7 @@ public final class DefaultsAndOverrides
         else
         {
             Ice.EndpointSelectionTypeParseException ex = new Ice.EndpointSelectionTypeParseException();
-            ex.str = value;
+            ex.str = "illegal value `" + value + "'; expected `Random' or `Ordered'";
             throw ex;
         }
 
diff --git a/java/src/IceInternal/EndpointFactoryManager.java b/java/src/IceInternal/EndpointFactoryManager.java
index de816428863..50b5e8d2ac7 100644
--- a/java/src/IceInternal/EndpointFactoryManager.java
+++ b/java/src/IceInternal/EndpointFactoryManager.java
@@ -51,7 +51,7 @@ public final class EndpointFactoryManager
         if(s.length() == 0)
         {
             Ice.EndpointParseException e = new Ice.EndpointParseException();
-            e.str = str;
+            e.str = "value has no non-whitespace characters";
             throw e;
         }
 
diff --git a/java/src/IceInternal/OpaqueEndpointI.java b/java/src/IceInternal/OpaqueEndpointI.java
index f4c9a8e1f3a..c85e27fedea 100644
--- a/java/src/IceInternal/OpaqueEndpointI.java
+++ b/java/src/IceInternal/OpaqueEndpointI.java
@@ -30,7 +30,8 @@ final class OpaqueEndpointI extends EndpointI
             String option = arr[i++];
             if(option.length() != 2 || option.charAt(0) != '-')
             {
-                throw new Ice.EndpointParseException("opaque " + str);
+                throw new Ice.EndpointParseException("expected an endpoint option but found `" + option +
+                                                     "' in endpoint `opaque " + str + "'");
             }
 
             String argument = null;
@@ -45,7 +46,8 @@ final class OpaqueEndpointI extends EndpointI
                 {
                     if(argument == null)
                     {
-                        throw new Ice.EndpointParseException("opaque " + str);
+                        throw new Ice.EndpointParseException("no argument provided for -t option in endpoint `opaque "
+                                                             + str + "'");
                     }
 
                     int t;
@@ -55,16 +57,22 @@ final class OpaqueEndpointI extends EndpointI
                     }
                     catch(NumberFormatException ex)
                     {
-                        throw new Ice.EndpointParseException("opaque " + str);
+                        throw new Ice.EndpointParseException("invalid timeout value `" + argument +
+                                                             "' in endpoint `opaque " + str + "'");
                     }
 
                     if(t < 0 || t > 65535)
                     {
-                        throw new Ice.EndpointParseException("opaque " + str);
+                        throw new Ice.EndpointParseException("timeout value `" + argument +
+                                                             "' out of range in endpoint `opaque " + str + "'");
                     }
 
                     _type = (short)t;
                     ++topt;
+                    if(topt > 1)
+                    {
+                        throw new Ice.EndpointParseException("multiple -t options in endpoint `opaque " + str + "'");
+                    }
                     break;
                 }
 
@@ -72,30 +80,42 @@ final class OpaqueEndpointI extends EndpointI
                 {
                     if(argument == null)
                     {
-                        throw new Ice.EndpointParseException("opaque " + str);
+                        throw new Ice.EndpointParseException("no argument provided for -v option in endpoint `opaque "
+                                                             + str + "'");
                     }
                     for(int j = 0; j < argument.length(); ++j)
                     {
                         if(!IceUtilInternal.Base64.isBase64(argument.charAt(j)))
                         {
-                            throw new Ice.EndpointParseException("opaque " + str);
+                            throw new Ice.EndpointParseException("invalid base64 character `" + argument.charAt(j) +
+                                                                 "' (ordinal " + ((int)argument.charAt(j)) +
+                                                                 ") in endpoint `opaque " + str + "'");
                         }
                     }
                     _rawBytes = IceUtilInternal.Base64.decode(argument);
                     ++vopt;
+                    if(vopt > 1)
+                    {
+                        throw new Ice.EndpointParseException("multiple -v options in endpoint `opaque " + str + "'");
+                    }
                     break;
                 }
 
                 default:
                 {
-                    throw new Ice.EndpointParseException("opaque " + str);
+                    throw new Ice.EndpointParseException("invalid option `" + option + "' in endpoint `opaque " +
+                                                         str + "'");
                 }
             }
         }
 
-        if(topt != 1 || vopt != 1)
+        if(topt != 1)
+        {
+            throw new Ice.EndpointParseException("no -t option in endpoint `opaque " + str + "'");
+        }
+        if(vopt != 1)
         {
-            throw new Ice.EndpointParseException("opaque " + str);
+            throw new Ice.EndpointParseException("no -v option in endpoint `opaque " + str + "'");
         }
         calcHashValue();
     }
diff --git a/java/src/IceInternal/ReferenceFactory.java b/java/src/IceInternal/ReferenceFactory.java
index 30a236394ec..574c121b1e0 100644
--- a/java/src/IceInternal/ReferenceFactory.java
+++ b/java/src/IceInternal/ReferenceFactory.java
@@ -83,7 +83,7 @@ public final class ReferenceFactory
         if(beg == -1)
         {
             Ice.ProxyParseException e = new Ice.ProxyParseException();
-            e.str = s;
+            e.str = "no non-whitespace characters found in `" + s + "'";
             throw e;
         }
 
@@ -96,7 +96,7 @@ public final class ReferenceFactory
         if(end == -1)
         {
             Ice.ProxyParseException e = new Ice.ProxyParseException();
-            e.str = s;
+            e.str = "mismatched quotes around identity in `" + s + "'";
             throw e;
         }
         else if(end == 0)
@@ -118,7 +118,7 @@ public final class ReferenceFactory
         if(beg == end)
         {
             Ice.ProxyParseException e = new Ice.ProxyParseException();
-            e.str = s;
+            e.str = "no identity in `" + s + "'";
             throw e;
         }
 
@@ -148,7 +148,7 @@ public final class ReferenceFactory
             else if(IceUtilInternal.StringUtil.findFirstNotOf(s, delim, end) != -1)
             {
                 Ice.ProxyParseException e = new Ice.ProxyParseException();
-                e.str = s;
+                e.str = "invalid characters after identity in `" + s + "'";
                 throw e;
             }
             else
@@ -190,7 +190,7 @@ public final class ReferenceFactory
             if(option.length() != 2 || option.charAt(0) != '-')
             {
                 Ice.ProxyParseException e = new Ice.ProxyParseException();
-                e.str = s;
+                e.str = "expected a proxy option but found `" + option + "' in `" + s + "'";
                 throw e;
             }
 
@@ -211,7 +211,7 @@ public final class ReferenceFactory
                     if(end == -1)
                     {
                         Ice.ProxyParseException e = new Ice.ProxyParseException();
-                        e.str = s;
+                        e.str = "mismatched quotes around value for " + option + " option in `" + s + "'";
                         throw e;
                     }
                     else if(end == 0)
@@ -243,19 +243,21 @@ public final class ReferenceFactory
                     if(argument == null)
                     {
                         Ice.ProxyParseException e = new Ice.ProxyParseException();
-                        e.str = s;
+                        e.str = "no argument provided for -f option in `" + s + "'";
                         throw e;
                     }
 
-                    Ice.StringHolder facetH = new Ice.StringHolder();
-                    if(!IceUtilInternal.StringUtil.unescapeString(argument, 0, argument.length(), facetH))
+                    try
+                    {
+                        facet = IceUtilInternal.StringUtil.unescapeString(argument, 0, argument.length());
+                    }
+                    catch(IllegalArgumentException ex)
                     {
                         Ice.ProxyParseException e = new Ice.ProxyParseException();
-                        e.str = s;
+                        e.str = "invalid facet in `" + s + "': " + ex.getMessage();
                         throw e;
                     }
 
-                    facet = facetH.value;
                     break;
                 }
 
@@ -264,7 +266,7 @@ public final class ReferenceFactory
                     if(argument != null)
                     {
                         Ice.ProxyParseException e = new Ice.ProxyParseException();
-                        e.str = s;
+                        e.str = "unexpected argument `" + argument + "' provided for -t option in `" + s + "'";
                         throw e;
                     }
                     mode = Reference.ModeTwoway;
@@ -276,7 +278,7 @@ public final class ReferenceFactory
                     if(argument != null)
                     {
                         Ice.ProxyParseException e = new Ice.ProxyParseException();
-                        e.str = s;
+                        e.str = "unexpected argument `" + argument + "' provided for -o option in `" + s + "'";
                         throw e;
                     }
                     mode = Reference.ModeOneway;
@@ -288,7 +290,7 @@ public final class ReferenceFactory
                     if(argument != null)
                     {
                         Ice.ProxyParseException e = new Ice.ProxyParseException();
-                        e.str = s;
+                        e.str = "unexpected argument `" + argument + "' provided for -O option in `" + s + "'";
                         throw e;
                     }
                     mode = Reference.ModeBatchOneway;
@@ -300,7 +302,7 @@ public final class ReferenceFactory
                     if(argument != null)
                     {
                         Ice.ProxyParseException e = new Ice.ProxyParseException();
-                        e.str = s;
+                        e.str = "unexpected argument `" + argument + "' provided for -d option in `" + s + "'";
                         throw e;
                     }
                     mode = Reference.ModeDatagram;
@@ -312,7 +314,7 @@ public final class ReferenceFactory
                     if(argument != null)
                     {
                         Ice.ProxyParseException e = new Ice.ProxyParseException();
-                        e.str = s;
+                        e.str = "unexpected argument `" + argument + "' provided for -D option in `" + s + "'";
                         throw e;
                     }
                     mode = Reference.ModeBatchDatagram;
@@ -324,7 +326,7 @@ public final class ReferenceFactory
                     if(argument != null)
                     {
                         Ice.ProxyParseException e = new Ice.ProxyParseException();
-                        e.str = s;
+                        e.str = "unexpected argument `" + argument + "' provided for -s option in `" + s + "'";
                         throw e;
                     }
                     secure = true;
@@ -334,7 +336,7 @@ public final class ReferenceFactory
                 default:
                 {
                     Ice.ProxyParseException e = new Ice.ProxyParseException();
-                    e.str = s;
+                    e.str = "unknown option `" + option + "' in `" + s + "'";
                     throw e;
                 }
             }
@@ -412,8 +414,9 @@ public final class ReferenceFactory
             }
             if(endpoints.size() == 0)
             {
+                assert(!unknownEndpoints.isEmpty());
                 Ice.EndpointParseException e = new Ice.EndpointParseException();
-                e.str = unknownEndpoints.get(0);
+                e.str = "invalid endpoint `" + unknownEndpoints.get(0) + "' in `" + s + "'";
                 throw e;
             }
             else if(unknownEndpoints.size() != 0 &&
@@ -439,7 +442,7 @@ public final class ReferenceFactory
             if(beg == -1)
             {
                 Ice.ProxyParseException e = new Ice.ProxyParseException();
-                e.str = s;
+                e.str = "missing adapter id in `" + s + "'";
                 throw e;
             }
 
@@ -448,7 +451,7 @@ public final class ReferenceFactory
             if(end == -1)
             {
                 Ice.ProxyParseException e = new Ice.ProxyParseException();
-                e.str = s;
+                e.str = "mismatched quotes around adapter id in `" + s + "'";
                 throw e;
             }
             else if(end == 0)
@@ -470,24 +473,31 @@ public final class ReferenceFactory
             if(end != s.length() && IceUtilInternal.StringUtil.findFirstNotOf(s, delim, end) != -1)
             {
                 Ice.ProxyParseException e = new Ice.ProxyParseException();
-                e.str = s;
+                e.str = "invalid trailing characters after `" + s.substring(0, end + 1) + "' in `" + s + "'";
                 throw e;
             }
-            
-            Ice.StringHolder token = new Ice.StringHolder();
-            if(!IceUtilInternal.StringUtil.unescapeString(adapterstr, 0, adapterstr.length(), token) ||
-               token.value.length() == 0)
+
+            try
+            {
+                adapter = IceUtilInternal.StringUtil.unescapeString(adapterstr, 0, adapterstr.length());
+            }
+            catch(IllegalArgumentException ex)
+            {
+                Ice.ProxyParseException e = new Ice.ProxyParseException();
+                e.str = "invalid adapter id in `" + s + "': " + ex.getMessage();
+                throw e;
+            }
+            if(adapter.length() == 0)
             {
                 Ice.ProxyParseException e = new Ice.ProxyParseException();
-                e.str = s;
+                e.str = "empty adapter id in `" + s + "'";
                 throw e;
             }
-            adapter = token.value;
             return create(ident, facet, mode, secure, null, adapter, propertyPrefix);
         }
 
         Ice.ProxyParseException ex = new Ice.ProxyParseException();
-        ex.str = s;
+        ex.str = "malformed proxy `" + s + "'";
         throw ex;
     }
 
@@ -782,7 +792,8 @@ public final class ReferenceFactory
                 }
                 else
                 {
-                    throw new Ice.EndpointSelectionTypeParseException(type);
+                    throw new Ice.EndpointSelectionTypeParseException("illegal value `" + type +
+                                                                      "'; expected `Random' or `Ordered'");
                 }
             }
         
diff --git a/java/src/IceInternal/TcpEndpointI.java b/java/src/IceInternal/TcpEndpointI.java
index 27618d8ccc5..f331068a9e8 100644
--- a/java/src/IceInternal/TcpEndpointI.java
+++ b/java/src/IceInternal/TcpEndpointI.java
@@ -46,7 +46,8 @@ final class TcpEndpointI extends EndpointI
             String option = arr[i++];
             if(option.length() != 2 || option.charAt(0) != '-')
             {
-                throw new Ice.EndpointParseException("tcp " + str);
+                throw new Ice.EndpointParseException("expected an endpoint option but found `" + option +
+                                                     "' in endpoint `tcp " + str + "'");
             }
 
             String argument = null;
@@ -65,7 +66,8 @@ final class TcpEndpointI extends EndpointI
                 {
                     if(argument == null)
                     {
-                        throw new Ice.EndpointParseException("tcp " + str);
+                        throw new Ice.EndpointParseException("no argument provided for -h option in endpoint `tcp "
+                                                             + str + "'");
                     }
 
                     _host = argument;
@@ -76,7 +78,8 @@ final class TcpEndpointI extends EndpointI
                 {
                     if(argument == null)
                     {
-                        throw new Ice.EndpointParseException("tcp " + str);
+                        throw new Ice.EndpointParseException("no argument provided for -p option in endpoint `tcp "
+                                                             + str + "'");
                     }
 
                     try
@@ -85,12 +88,14 @@ final class TcpEndpointI extends EndpointI
                     }
                     catch(NumberFormatException ex)
                     {
-                        throw new Ice.EndpointParseException("tcp " + str);
+                        throw new Ice.EndpointParseException("invalid port value `" + argument +
+                                                             "' in endpoint `tcp " + str + "'");
                     }
 
                     if(_port < 0 || _port > 65535)
                     {
-                        throw new Ice.EndpointParseException("tcp " + str);
+                        throw new Ice.EndpointParseException("port value `" + argument +
+                                                             "' out of range in endpoint `tcp " + str + "'");
                     }
 
                     break;
@@ -100,7 +105,8 @@ final class TcpEndpointI extends EndpointI
                 {
                     if(argument == null)
                     {
-                        throw new Ice.EndpointParseException("tcp " + str);
+                        throw new Ice.EndpointParseException("no argument provided for -t option in endpoint `tcp "
+                                                             + str + "'");
                     }
 
                     try
@@ -109,7 +115,8 @@ final class TcpEndpointI extends EndpointI
                     }
                     catch(NumberFormatException ex)
                     {
-                        throw new Ice.EndpointParseException("tcp " + str);
+                        throw new Ice.EndpointParseException("invalid timeout value `" + argument +
+                                                             "' in endpoint `tcp " + str + "'");
                     }
 
                     break;
@@ -119,7 +126,8 @@ final class TcpEndpointI extends EndpointI
                 {
                     if(argument != null)
                     {
-                        throw new Ice.EndpointParseException("tcp " + str);
+                        throw new Ice.EndpointParseException("unexpected argument `" + argument +
+                                                             "' provided for -z option in `tcp " + str + "'");
                     }
 
                     _compress = true;
@@ -128,7 +136,7 @@ final class TcpEndpointI extends EndpointI
 
                 default:
                 {
-                    throw new Ice.EndpointParseException("tcp " + str);
+                    throw new Ice.EndpointParseException("unknown option `" + option + "' in `tcp " + str + "'");
                 }
             }
         }
@@ -145,7 +153,7 @@ final class TcpEndpointI extends EndpointI
             }
             else
             {
-                throw new Ice.EndpointParseException("tcp " + str);
+                throw new Ice.EndpointParseException("`-h *' not valid for proxy endpoint `tcp " + str + "'");
             }
         }
 
diff --git a/java/src/IceInternal/UdpEndpointI.java b/java/src/IceInternal/UdpEndpointI.java
index 880eae25473..153b9f99a96 100644
--- a/java/src/IceInternal/UdpEndpointI.java
+++ b/java/src/IceInternal/UdpEndpointI.java
@@ -57,7 +57,8 @@ final class UdpEndpointI extends EndpointI
             String option = arr[i++];
             if(option.charAt(0) != '-')
             {
-                throw new Ice.EndpointParseException("udp " + str);
+                throw new Ice.EndpointParseException("expected an endpoint option but found `" + option +
+                                                     "' in endpoint `udp " + str + "'");
             }
 
             String argument = null;
@@ -74,13 +75,15 @@ final class UdpEndpointI extends EndpointI
             {
                 if(argument == null)
                 {
-                    throw new Ice.EndpointParseException("udp " + str);
+                    throw new Ice.EndpointParseException("no argument provided for -v option in endpoint `udp "
+                                                         + str + "'");
                 }
 
                 int pos = argument.indexOf('.');
                 if(pos == -1)
                 {
-                    throw new Ice.EndpointParseException("udp " + str);
+                    throw new Ice.EndpointParseException("malformed protocol version `" + argument +
+                                                         "' in endpoint `udp " + str + "'");
                 }
 
                 String majStr = argument.substring(0, pos);
@@ -94,12 +97,14 @@ final class UdpEndpointI extends EndpointI
                 }
                 catch(NumberFormatException ex)
                 {
-                    throw new Ice.EndpointParseException("udp " + str);
+                    throw new Ice.EndpointParseException("invalid protocol version `" + argument +
+                                                         "' in endpoint `udp " + str + "'");
                 }
 
                 if(majVersion < 1 || majVersion > 255 || minVersion < 0 || minVersion > 255)
                 {
-                    throw new Ice.EndpointParseException("udp " + str);
+                    throw new Ice.EndpointParseException("range error in protocol version `" + argument +
+                                                         "' in endpoint `udp " + str + "'");
                 }
 
                 if(majVersion != Protocol.protocolMajor)
@@ -119,13 +124,15 @@ final class UdpEndpointI extends EndpointI
             {
                 if(argument == null)
                 {
-                    throw new Ice.EndpointParseException("udp " + str);
+                    throw new Ice.EndpointParseException("no argument provided for -e option in endpoint `udp "
+                                                         + str + "'");
                 }
 
                 int pos = argument.indexOf('.');
                 if(pos == -1)
                 {
-                    throw new Ice.EndpointParseException("udp " + str);
+                    throw new Ice.EndpointParseException("malformed encoding version `" + argument +
+                                                         "' in endpoint `udp " + str + "'");
                 }
 
                 String majStr = argument.substring(0, pos);
@@ -139,12 +146,14 @@ final class UdpEndpointI extends EndpointI
                 }
                 catch(NumberFormatException ex)
                 {
-                    throw new Ice.EndpointParseException("udp " + str);
+                    throw new Ice.EndpointParseException("invalid encoding version `" + argument +
+                                                         "' in endpoint `udp " + str + "'");
                 }
 
                 if(majVersion < 1 || majVersion > 255 || minVersion < 0 || minVersion > 255)
                 {
-                    throw new Ice.EndpointParseException("udp " + str);
+                    throw new Ice.EndpointParseException("range error in encoding version `" + argument +
+                                                         "' in endpoint `udp " + str + "'");
                 }
 
                 if(majVersion != Protocol.encodingMajor)
@@ -164,7 +173,8 @@ final class UdpEndpointI extends EndpointI
             {
                 if(argument == null)
                 {
-                    throw new Ice.EndpointParseException("udp " + str);
+                    throw new Ice.EndpointParseException("no argument provided for -h option in endpoint `udp "
+                                                         + str + "'");
                 }
 
                 _host = argument;
@@ -173,7 +183,8 @@ final class UdpEndpointI extends EndpointI
             {
                 if(argument == null)
                 {
-                    throw new Ice.EndpointParseException("udp " + str);
+                    throw new Ice.EndpointParseException("no argument provided for -p option in endpoint `udp "
+                                                         + str + "'");
                 }
 
                 try
@@ -182,19 +193,22 @@ final class UdpEndpointI extends EndpointI
                 }
                 catch(NumberFormatException ex)
                 {
-                    throw new Ice.EndpointParseException("udp " + str);
+                    throw new Ice.EndpointParseException("invalid port value `" + argument + "' in endpoint `udp " +
+                                                         str + "'");
                 }
 
                 if(_port < 0 || _port > 65535)
                 {
-                    throw new Ice.EndpointParseException("udp " + str);
+                    throw new Ice.EndpointParseException("port value `" + argument +
+                                                         "' out of range in endpoint `udp " + str + "'");
                 }
             }
             else if(option.equals("-c"))
             {
                 if(argument != null)
                 {
-                    throw new Ice.EndpointParseException("udp " + str);
+                    throw new Ice.EndpointParseException("unexpected argument `" + argument +
+                                                         "' provided for -c option in `udp " + str + "'");
                 }
 
                 _connect = true;
@@ -204,7 +218,8 @@ final class UdpEndpointI extends EndpointI
             {
                 if(argument != null)
                 {
-                    throw new Ice.EndpointParseException("udp " + str);
+                    throw new Ice.EndpointParseException("unexpected argument `" + argument +
+                                                         "' provided for -z option in `udp " + str + "'");
                 }
 
                 _compress = true;
@@ -214,7 +229,8 @@ final class UdpEndpointI extends EndpointI
             {
                 if(argument == null)
                 {
-                    throw new Ice.EndpointParseException("udp " + str);
+                    throw new Ice.EndpointParseException("no argument provided for --interface option in endpoint `udp "
+                                                         + str + "'");
                 }
 
                 _mcastInterface = argument;
@@ -223,7 +239,8 @@ final class UdpEndpointI extends EndpointI
             {
                 if(argument == null)
                 {
-                    throw new Ice.EndpointParseException("udp " + str);
+                    throw new Ice.EndpointParseException("no argument provided for --ttl option in endpoint `udp "
+                                                         + str + "'");
                 }
 
                 try
@@ -232,17 +249,19 @@ final class UdpEndpointI extends EndpointI
                 }
                 catch(NumberFormatException ex)
                 {
-                    throw new Ice.EndpointParseException("udp " + str);
+                    throw new Ice.EndpointParseException("invalid TTL value `" + argument + "' in endpoint `udp " +
+                                                         str + "'");
                 }
 
                 if(_mcastTtl < 0)
                 {
-                    throw new Ice.EndpointParseException("udp " + str);
+                    throw new Ice.EndpointParseException("TTL value `" + argument +
+                                                         "' out of range in endpoint `udp " + str + "'");
                 }
             }
             else
             {
-                throw new Ice.EndpointParseException("udp " + str);
+                throw new Ice.EndpointParseException("unknown option `" + option + "' in `udp " + str + "'");
             }
         }
 
@@ -258,7 +277,7 @@ final class UdpEndpointI extends EndpointI
             }
             else
             {
-                throw new Ice.EndpointParseException("udp " + str);
+                throw new Ice.EndpointParseException("`-h *' not valid for proxy endpoint `udp " + str + "'");
             }
         }
 
diff --git a/java/src/IceSSL/EndpointI.java b/java/src/IceSSL/EndpointI.java
index 9c0282750da..97837176a0c 100644
--- a/java/src/IceSSL/EndpointI.java
+++ b/java/src/IceSSL/EndpointI.java
@@ -46,7 +46,8 @@ final class EndpointI extends IceInternal.EndpointI
             String option = arr[i++];
             if(option.length() != 2 || option.charAt(0) != '-')
             {
-                throw new Ice.EndpointParseException("ssl " + str);
+                throw new Ice.EndpointParseException("expected an endpoint option but found `" + option +
+                                                     "' in endpoint `ssl " + str + "'");
             }
 
             String argument = null;
@@ -65,7 +66,8 @@ final class EndpointI extends IceInternal.EndpointI
                 {
                     if(argument == null)
                     {
-                        throw new Ice.EndpointParseException("ssl " + str);
+                        throw new Ice.EndpointParseException("no argument provided for -h option in endpoint `ssl "
+                                                             + str + "'");
                     }
 
                     _host = argument;
@@ -76,7 +78,8 @@ final class EndpointI extends IceInternal.EndpointI
                 {
                     if(argument == null)
                     {
-                        throw new Ice.EndpointParseException("ssl " + str);
+                        throw new Ice.EndpointParseException("no argument provided for -p option in endpoint `ssl "
+                                                             + str + "'");
                     }
 
                     try
@@ -85,12 +88,14 @@ final class EndpointI extends IceInternal.EndpointI
                     }
                     catch(NumberFormatException ex)
                     {
-                        throw new Ice.EndpointParseException("ssl " + str);
+                        throw new Ice.EndpointParseException("invalid port value `" + argument +
+                                                             "' in endpoint `ssl " + str + "'");
                     }
 
                     if(_port < 0 || _port > 65535)
                     {
-                        throw new Ice.EndpointParseException("ssl " + str);
+                        throw new Ice.EndpointParseException("port value `" + argument +
+                                                             "' out of range in endpoint `ssl " + str + "'");
                     }
 
                     break;
@@ -100,7 +105,8 @@ final class EndpointI extends IceInternal.EndpointI
                 {
                     if(argument == null)
                     {
-                        throw new Ice.EndpointParseException("ssl " + str);
+                        throw new Ice.EndpointParseException("no argument provided for -t option in endpoint `ssl "
+                                                             + str + "'");
                     }
 
                     try
@@ -109,7 +115,8 @@ final class EndpointI extends IceInternal.EndpointI
                     }
                     catch(NumberFormatException ex)
                     {
-                        throw new Ice.EndpointParseException("ssl " + str);
+                        throw new Ice.EndpointParseException("invalid timeout value `" + argument +
+                                                             "' in endpoint `ssl " + str + "'");
                     }
 
                     break;
@@ -119,7 +126,8 @@ final class EndpointI extends IceInternal.EndpointI
                 {
                     if(argument != null)
                     {
-                        throw new Ice.EndpointParseException("ssl " + str);
+                        throw new Ice.EndpointParseException("unexpected argument `" + argument +
+                                                             "' provided for -z option in `ssl " + str + "'");
                     }
 
                     _compress = true;
@@ -128,7 +136,7 @@ final class EndpointI extends IceInternal.EndpointI
 
                 default:
                 {
-                    throw new Ice.EndpointParseException("ssl " + str);
+                    throw new Ice.EndpointParseException("unknown option `" + option + "' in `ssl " + str + "'");
                 }
             }
         }
@@ -145,7 +153,7 @@ final class EndpointI extends IceInternal.EndpointI
             }
             else
             {
-                throw new Ice.EndpointParseException("ssl " + str);
+                throw new Ice.EndpointParseException("`-h *' not valid for proxy endpoint `ssl " + str + "'");
             }
         }
 
diff --git a/java/src/IceUtilInternal/StringUtil.java b/java/src/IceUtilInternal/StringUtil.java
index befc624f425..137bb234e06 100644
--- a/java/src/IceUtilInternal/StringUtil.java
+++ b/java/src/IceUtilInternal/StringUtil.java
@@ -199,11 +199,22 @@ public final class StringUtil
     }
 
     private static char
-    checkChar(char c)
+    checkChar(String s, int pos)
     {
+        char c = s.charAt(pos);
         if(!(c >= 32 && c <= 126))
         {
-            throw new IllegalArgumentException("illegal input character");
+            String msg;
+            if(pos > 0)
+            {
+                msg = "character after `" + s.substring(0, pos) + "'";
+            }
+            else
+            {
+                msg = "first character";
+            }
+            msg += " is not a printable ASCII character (ordinal " + (int)c + ")";
+            throw new IllegalArgumentException(msg);
         }
         return c;
     }
@@ -223,13 +234,13 @@ public final class StringUtil
 
         if(s.charAt(start) != '\\')
         {
-            c = checkChar(s.charAt(start++));
+            c = checkChar(s, start++);
         }
         else
         {
             if(start + 1 == end)
             {
-                throw new IllegalArgumentException("trailing backslash in argument");
+                throw new IllegalArgumentException("trailing backslash");
             }
             switch(s.charAt(++start))
             {
@@ -279,7 +290,7 @@ public final class StringUtil
                 case '6':
                 case '7':
                 {
-                    int oct = 0;
+                    int val = 0;
                     for(int j = 0; j < 3 && start < end; ++j)
                     {
                         int charVal = s.charAt(start++) - '0';
@@ -288,18 +299,19 @@ public final class StringUtil
                             --start;
                             break;
                         }
-                        oct = oct * 8 + charVal;
+                        val = val * 8 + charVal;
                     }
-                    if(oct > 255)
+                    if(val > 255)
                     {
-                        throw new IllegalArgumentException("octal value out of range");
+                        String msg = "octal value \\" + Integer.toOctalString(val) + " (" + val + ") is out of range";
+                        throw new IllegalArgumentException(msg);
                     }
-                    c = (char)oct;
+                    c = (char)val;
                     break;
                 }
                 default:
                 {
-                    c = checkChar(s.charAt(start++));
+                    c = checkChar(s, start++);
                     break;
                 }
             }
@@ -324,42 +336,33 @@ public final class StringUtil
     }
 
     //
-    // Remove escape sequences added by escapeString.
+    // Remove escape sequences added by escapeString. Throws IllegalArgumentException
+    // for an invalid input string.
     //
-    public static boolean
-    unescapeString(String s, int start, int end, Ice.StringHolder result)
+    public static String
+    unescapeString(String s, int start, int end)
     {
-        if(start < 0)
-        {
-            throw new IllegalArgumentException("start offset must be >= 0");
-        }
-        if(end > s.length())
-        {
-            throw new IllegalArgumentException("end offset must <= s.length()");
-        }
-        if(start > end)
+        assert(start >= 0 && start <= end && end <= s.length());
+
+        StringBuilder sb = new StringBuilder(end - start);
+        decodeString(s, start, end, sb);
+        String decodedString = sb.toString();
+
+        byte[] arr = new byte[decodedString.length()];
+        for(int i = 0; i < arr.length; ++i)
         {
-            throw new IllegalArgumentException("start offset must <= end offset");
+            arr[i] = (byte)decodedString.charAt(i);
         }
 
         try
         {
-            StringBuilder sb = new StringBuilder(end - start);
-            decodeString(s, start, end, sb);
-            String decodedString = sb.toString();
-
-            byte[] arr = new byte[decodedString.length()];
-            for(int i = 0; i < arr.length; ++i)
-            {
-                arr[i] = (byte)decodedString.charAt(i);
-            }
-
-            result.value = new String(arr, 0, arr.length, "UTF8");
-            return true;
+            return new String(arr, 0, arr.length, "UTF8");
         }
-        catch(java.lang.Exception ex)
+        catch(java.io.UnsupportedEncodingException ex)
         {
-            return false;
+            IllegalArgumentException e = new IllegalArgumentException("unsupported encoding");
+            e.initCause(ex);
+            throw e;
         }
     }
 
diff --git a/java/test/Ice/proxy/AllTests.java b/java/test/Ice/proxy/AllTests.java
index 39d772b08e9..678a0b9cf52 100644
--- a/java/test/Ice/proxy/AllTests.java
+++ b/java/test/Ice/proxy/AllTests.java
@@ -99,12 +99,34 @@ public class AllTests
         test(b1.ice_getIdentity().name.equals("test\1114test"));
 
         b1 = communicator.stringToProxy("test\\b\\f\\n\\r\\t\\'\\\"\\\\test");
-        test(b1.ice_getIdentity().name.equals("test\b\f\n\r\t\'\"\\test") && b1.ice_getIdentity().category.length() == 0);
+        test(b1.ice_getIdentity().name.equals("test\b\f\n\r\t\'\"\\test") &&
+             b1.ice_getIdentity().category.length() == 0);
 
         b1 = communicator.stringToProxy("category/test");
         test(b1.ice_getIdentity().name.equals("test") && b1.ice_getIdentity().category.equals("category") &&
              b1.ice_getAdapterId().length() == 0);
-             
+
+        b1 = communicator.stringToProxy("");
+        test(b1 == null);
+        b1 = communicator.stringToProxy("\"\"");
+        test(b1 == null);
+        try
+        {
+            b1 = communicator.stringToProxy("\"\" test"); // Invalid trailing characters.
+            test(false);
+        }
+        catch(Ice.ProxyParseException ex)
+        {
+        }
+        try
+        {
+            b1 = communicator.stringToProxy("test:"); // Missing endpoint.
+            test(false);
+        }
+        catch(Ice.EndpointParseException ex)
+        {
+        }
+
         b1 = communicator.stringToProxy("test@adapter");
         test(b1.ice_getIdentity().name.equals("test") && b1.ice_getIdentity().category.length() == 0 &&
              b1.ice_getAdapterId().equals("adapter"));
@@ -637,7 +659,7 @@ public class AllTests
             Ice.ObjectPrx p1 = communicator.stringToProxy("test:opaque -t 1 -v CTEyNy4wLjAuMeouAAAQJwAAAA==");
             String pstr = communicator.proxyToString(p1);
             test(pstr.equals("test -t:tcp -h 127.0.0.1 -p 12010 -t 10000"));
-        
+
             // Working?
             boolean ssl = communicator.getProperties().getProperty("Ice.Default.Protocol").equals("ssl");
             if(!ssl)
diff --git a/slice/Ice/Communicator.ice b/slice/Ice/Communicator.ice
index 1641adf4815..16fce736278 100644
--- a/slice/Ice/Communicator.ice
+++ b/slice/Ice/Communicator.ice
@@ -124,7 +124,8 @@ local interface Communicator
      * having an identity with a name "MyObject" and a category
      * "MyCategory", with the server running on host "some_host", port
      * 10000. If the string does not parse correctly, the operation
-     * throws {@link ProxyParseException}.
+     * throws one of {@link ProxyParseException},
+     * {@link EndpointParseException}, or {@link IdentityParseException}.
      *
      * @param str The string to convert into a proxy.
      *
@@ -175,7 +176,8 @@ local interface Communicator
 
     /**
      *
-     * Convert a string into an identity.
+     * Convert a string into an identity. If the string does not parse
+     * correctly, the operation throws {@link IdentityParseException}.
      *
      * @param str The string to convert into an identity.
      *