What are all possible reason when (HttpServletRequest).isRequestedSessionIdValid() will return false.
The actual problem is :
I got log out from application even when i was working on application few minutes back. Time out specified in web.xml is 240 i.e. 4 hrs. In log file i found that the method isRequestedSessionIdValid is returning false and HttpSession object reset to null. I am using JBoss as application server.