Symptoms

Server Error in '/Designer' 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'.
 

Diagnoses

Google search on the issue shows that there is a Microsoft Kb article on it.
 

Resolution

According to Microsoft kb article (https://support.microsoft.com/en-us/kb/2015129):

"This issue occurs because the Applicationhost.config file for Windows Process Activation Service (WAS) has the following section defined, and this section is incompatible with the .NET Framework 4.0:



This section should be defined as follows:



Note: You can find the Applicationhost.config file in the following location: %windir%system32inetsrvconfig"

Running this command ( C:WindowsMicrosoft.NETFrameworkv4.0.30319aspnet_regiis -iru ) resolved the issue.