title: Weird 500 Internal Server Error (firebug, php, display_errors, ajax)
body: <p>On one page I am doing multiple AJAX calls. All calls return responses successfully but the last one (not related to other ajax calls) returns 500 internal server error as response code (as firebug tells). However, in spite of error code, correct content is returned from that AJAX call. </p>
  
  <p>To my amazement, when I set display_errors option in php.ini as On, the error disappears and response in rendered on the page. I have setup error logging to a file but no error is logged corresponding to the above mentioned internal server error.</p>
  
  <p>By the way, I am using Apache, JQuery, PHP5, APC (if it is relevant).</p>