title: Session timeout and csrf token error in Symfony2 forms
body: <p>I'm facing the 'CSRF token invalid, please resubmit the form' issue when a user has a page displayed for longer than the session expiry and then try to submit the Symfony form. It throws token mismatch at the form validation step in my Symfony controller. How do you guys handle this? How can I catch it ? Do I have to activate csrf validation no matter what or is there certain type of forms which don't need that verification ? </p>
  
  <p>I just saw that people recommend to set the Symfony session timeout to 0 in the config.yml. Is that a good way to prevent this ?</p>
  
  <p>Thanks</p>