Ambiguous Match Found - OMG!

*Deep breath*

Ambiguous match found.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Reflection.AmbiguousMatchException: Ambiguous match found.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:


[AmbiguousMatchException: Ambiguous match found.]
System.RuntimeType.GetPropertyImpl(String name, BindingFlags bindingAttr, Binder binder, Type returnType, Type[] types, ParameterModifier[] modifiers) +245
System.Type.GetProperty(String name, BindingFlags bindingAttr) +24
System.Web.UI.Util.GetNonPrivatePropertyType(Type classType, String propName) +9
System.Web.Compilation.TemplateControlCompiler.BuildFieldDeclaration(ControlBuilder builder, Boolean fGeneratedID) +48
System.Web.Compilation.TemplateControlCompiler.BuildSourceDataTreeFromBuilder(ControlBuilder builder, Boolean fInTemplate, PropertySetterEntry pse) +776
System.Web.Compilation.TemplateControlCompiler.BuildSourceDataTreeFromBuilder(ControlBuilder builder, Boolean fInTemplate, PropertySetterEntry pse) +352
System.Web.Compilation.TemplateControlCompiler.BuildSourceDataTreeFromBuilder(ControlBuilder builder, Boolean fInTemplate, PropertySetterEntry pse) +352
System.Web.Compilation.TemplateControlCompiler.BuildMiscClassMembers() +51
System.Web.Compilation.PageCompiler.BuildMiscClassMembers() +10
System.Web.Compilation.BaseCompiler.BuildSourceDataTree() +1279
System.Web.Compilation.BaseCompiler.GetCompiledType() +129
System.Web.UI.PageParser.CompileIntoType() +59
System.Web.UI.TemplateParser.GetParserCacheItemThroughCompilation() +126

[HttpException (0x80004005): Ambiguous match found.]
System.Web.UI.TemplateParser.GetParserCacheItemInternal(Boolean fCreateIfNotFound) +947
System.Web.UI.TemplateParser.GetParserCacheItemWithNewConfigPath() +125
System.Web.UI.TemplateParser.GetParserCacheItem() +88
System.Web.UI.TemplateControlParser.CompileAndGetParserCacheItem(String virtualPath, String inputFile, HttpContext context) +116
System.Web.UI.TemplateControlParser.GetCompiledInstance(String virtualPath, String inputFile, HttpContext context) +36
System.Web.UI.PageParser.GetCompiledPageInstanceInternal(String virtualPath, String inputFile, HttpContext context) +43
System.Web.UI.PageHandlerFactory.GetHandler(HttpContext context, String requestType, String url, String path) +44
System.Web.HttpApplication.MapHttpHandler(HttpContext context, String requestType, String path, String pathTranslated, Boolean useAppConfig) +699
System.Web.MapHandlerExecutionStep.System.Web.HttpApplication+IExecutionStep.Execute() +95
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +173

Thread moved to ASP.Net forum

Explain your situation. Explain what you're doing. Tell us your ASP.NET version. Show your code and point out which line it's happening at.

This looks like it's related to namespaces.