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.
Resolution:There are two ways of resolving this problem.
1) You can use other session state mode like State Server or SQL server which supports multiple worker processes.
2) Set your maximum number of worker process to 1 in IIS 7/7.5 application pool advance settings.
I have changed the same and again it started working again.
That's it. Hope you like it. Sty tuned for more..