Could Not Load Type ‘System.ServiceModel.Activation.HttpModule’

This error will happen when WCF Activation Services is installed AFTER .Net 4.0 Framework. To fix, open a command prompt in the .Net 4.0 directory:

 

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

 

and run the following command:

 

aspnet_regiis.exe -iru