In this post I am going to explain about reason for InProcsessionState was not working with IIS 7.5. Problem: Yesterday in one of my PC I got updated IIS 7.5 and suddenly after updating the IIS my ASP.NET application session state stopped working. It was a very weird behaviour and after doing some R and D I have found that my worker process per application was more then one. That was the reason for the session state was not working as “InProc” session state is using IIS memory to manage sessions. You can find more information about this in following link.