Last days I installed a new ConfigMgr 2012 demo environment. Everything was working fine after installation on my server, but when accessing a client it went wrong. It wasn't possible to start the Self Service Application Catalog from within the Software Center.
The following error message was displayed here:
Could not load type 'System.ServiceModel.Activation.HttpModule' from assembly 'System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'
Good news is there's an easy solution for this, which can be find on: Microsoft Support
To resolve this issue, run the following command line:
aspnet_regiis.exe /iru
The Aspnet_regiis.exe file can be found in one of the following locations:
%windir%\Microsoft.NET\Framework\v4.0.30319 (x86 computer)
%windir%\Microsoft.NET\Framework64\v4.0.30319 (x64 computer)
Cause of this has something to do with IIS and .NET installation order. After run this command the Self Service Application Catalog is working! Now it's possible to use this great new functionality.