title: Symfony 2 - Fatal error: Cannot redeclare class SessionHandlerInterface in C:\...\app\cache\dev\classes.php on line 532
body: <p>After reinstalling my wamp environment this error message is showing on screen after I open app_dev.php:</p>
  
  <blockquote>
    <p>Fatal error: Cannot redeclare class SessionHandlerInterface in C:...\app\cache\dev\classes.php on line 532</p>
  </blockquote>
  
  <p>Does anyone have any clue what is going wrong?</p>