When you try to access the Microsoft Dynamics CRM 2011 Web client, you get the following error.
Could not load type ‘System.ServiceModel.Activation.HttpModule’ from assembly ‘System.ServiceModel, Version=126.96.36.199, Culture=neutral, PublicKeyToken=b77a5c561934e089
This error can occur when there are multiple versions of the .NET Framework on the computer that is running IIS, and IIS was installed after .NET Framework 4.0 or before the Service Model in Windows Communication Foundation was registered.
1. Go to computer where CRM 2011 is installed and open command prompt.
2. Change the directory to C:\windows\Microsoft.NET\Framework64\v4.0.30319
3. Type the following command- aspnet_regiis.exe -iru
4. Reset the IIS by iisreset command.