You receive a System.InvalidOperationException exception error when you run a Microsoft .NET Framework 2.0-based application after you install security update MS 07-040 on a computer


When you run a Microsoft .NET Framework 2.0-based application, you receive a System.InvalidOperationException exception. This problem occurs if the following conditions are true:
  • You have installed security update MS 07-040 on the computer.
  • The .NET Framework 2.0-based application contains several enum types.
  • The enum types contain the XmlType attribute.
  • You set the AnonymousType field to True in the XmlType attribute.
If you have not installed security update MS 07-040 on the computer, you do not receive the exception.

If you change the AnonymousType field to False, you do not receive the exception even if you have installed security update MS 07-040.


Hotfix information

A supported hotfix is now available from Microsoft. However, it is intended to correct only the problem that is described in this article. Apply it only to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Customer Support Services to obtain the hotfix. For a complete list of Microsoft Customer Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.


To apply this hotfix, you must have the .NET Framework 2.0 SP1 installed.

Restart requirement

You have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.
File nameFile versionFile sizeDateTimePlatform

More Information

When this issue occurs, the call stack that is generated resembles the following:
System.InvalidOperationException was unhandled
Message="Unable to generate a temporary class (result=1).\r\nerror CS0266: Cannot implicitly convert type 'ConsoleApplication2.Color1?' to 'ConsoleApplication2.Color2?'. An explicit conversion exists (are you missing a cast?)\r\n"
at System.Xml.Serialization.Compiler.Compile(Assembly parent, String ns, XmlSerializerCompilerParameters xmlParameters, Evidence evidence)
at System.Xml.Serialization.TempAssembly.GenerateAssembly(XmlMapping[] xmlMappings, Type[] types, String defaultNamespace, Evidence evidence, XmlSerializerCompilerParameters parameters, Assembly assembly, Hashtable assemblies)
at System.Xml.Serialization.TempAssembly..ctor(XmlMapping[] xmlMappings, Type[] types, String defaultNamespace, String location, Evidence evidence)
at System.Xml.Serialization.XmlSerializer.GenerateTempAssembly(XmlMapping xmlMapping, Type type, String defaultNamespace)
at System.Xml.Serialization.XmlSerializer..ctor(Type type, String defaultNamespace)
at ConsoleApplication2.Program.Main(String[] args) in C:\Users\daroth\Documents\Visual Studio 2008\Projects\DevDivBugs162210\ConsoleApplication2\Program.cs:line 48
at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)
at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
For more information, click the following article number to view the article in the Microsoft Knowledge Base:
931212 MS07-040: Vulnerabilities in the .NET Framework could allow remote code execution

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:
824684 Description of the standard terminology that is used to describe Microsoft software updates


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section of this article.

Article ID: 948233 - Last Review: Jun 21, 2014 - Revision: 1