When attempting to run a service that receives messages over the HTTP transport, you may receive an error similar to the following:

Server Error in '/WCFApplication' 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. 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'.

This error can occur when IIS is installed after installing .NET Framework 4, or if the 3.0 version of the WCF Http Activation module is installed after installing IIS and .NET Framework 4.

To resolve this problem, you must use the ASP.NET IIS Registration Tool (Aspnet_regiis.exe,) to register the correct version of ASP.NET. This can be accomplished by using the –iru parameters when running aspnet_regiis.exe as follows:

aspnet_regiis.exe -iru