I would like to test session timeout problems while using IIS Express but I can't figure out how to modify the Session State setting so I can change the Time-out for Cookie Settings. Is this a modifiable setting?
Try following
1.In the web application's web.config file set sessionState timeout something like below (it is in minutes)
<sessionState timeout="30" />
2.Make sure that your application's app pool idle time out is greater than or equal to the timeout specified above (you can run the following command from the iisexpress installation folder)
appcmd set config /section:applicationPools /[name='YourAppPoolName'].processModel.idleTimeout:0.00:30:00