Hi got the solution. Actually I have used toke to login into my module and the token timeout was 5 second. If I Logged out and click on the back button of the browser before the 5 second then the Session_Start() event of glowal.ascx.cs is called again and read the token again and the create the session again. And if I click on the back button after the 5 second then session does not create. To solve this problem I does not allow the user to go to back through the browser. For this I have used the following code