title: app_dev.php works as expected, but app.php always gives a 503 error
body: <p>Recently created a new application and bundle in Symfony. No homepage is defined, so loading <code>http://localhost/app_dev.php</code> loads the default Symfony page, and all routes work as expected when using <code>app_dev.php</code></p>
  
  <p>However, when I try to load just <code>http://localhost</code> or any of the same routes without specifying <code>app_dev.php</code> in the address, it gives the message <code>503 Service Unavailable</code></p>
  
  <p>Any idea what could be causing this?</p>