Server Error in '/' Application.

Could not load type 'System.ServiceModel.Activation.HttpModule' from assembly 'System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.

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.TypeLoadException: Could not load type 'System.ServiceModel.Activation.HttpModule' from assembly 'System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.

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:

[TypeLoadException: Could not load type 'System.ServiceModel.Activation.HttpModule' from assembly 'System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.]
   System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMarkHandle stackMark, Boolean loadTypeFromPartialName, ObjectHandleOnStack type) +0
   System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark, Boolean loadTypeFromPartialName) +314
   System.Type.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase) +95
   System.Web.Compilation.BuildManager.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase) +124
   System.Web.Configuration.ConfigUtil.GetType(String typeName, String propertyName, ConfigurationElement configElement, XmlNode node, Boolean checkAptcaBit, Boolean ignoreCase) +76

[ConfigurationErrorsException: Could not load type 'System.ServiceModel.Activation.HttpModule' from assembly 'System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.]
   System.Web.Configuration.ConfigUtil.GetType(String typeName, String propertyName, ConfigurationElement configElement, XmlNode node, Boolean checkAptcaBit, Boolean ignoreCase) +11516844
   System.Web.Configuration.Common.ModulesEntry.SecureGetType(String typeName, String propertyName, ConfigurationElement configElement) +69
   System.Web.Configuration.Common.ModulesEntry..ctor(String name, String typeName, String propertyName, ConfigurationElement configElement) +62
   System.Web.HttpApplication.BuildIntegratedModuleCollection(List`1 moduleList) +264
   System.Web.HttpApplication.GetModuleCollection(IntPtr appContext) +1356
   Microsoft.Web.Infrastructure.DynamicModuleHelper.DynamicModuleReflectionUtil.GetIntegratedModuleCollection(HttpApplication target, IntPtr appContext) +34
   Microsoft.Web.Infrastructure.DynamicModuleHelper.CriticalStatics.Init(HttpApplication context) +269
   System.Web.HttpApplication.RegisterEventSubscriptionsWithIIS(IntPtr appContext, HttpContext context, MethodInfo[] handlers) +575
   System.Web.HttpApplication.InitSpecial(HttpApplicationState state, MethodInfo[] handlers, IntPtr appContext, HttpContext context) +352
   System.Web.HttpApplicationFactory.GetSpecialApplicationInstance(IntPtr appContext, HttpContext context) +407
   System.Web.Hosting.PipelineRuntime.InitializeApplication(IntPtr appContext) +375

[HttpException (0x80004005): Could not load type 'System.ServiceModel.Activation.HttpModule' from assembly 'System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +11686912
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +141
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +4863733

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.237

原因：在iis7或其他原.net 3.5的iis环境上安装.net4或更高版本后，没有更新注册

解决方案：

以.NET 4.0环境为例，执行以下Command：

cd "C:\Windows\Microsoft.NET\Framework64\v4.0.30319"

aspnet_regiis.exe -iru

引用：

http://social.msdn.microsoft.com/Forums/en/wcf/thread/39571e42-aca7-469d-8c68-aa59c2da4fcc