Symfony 2 - 404 Not Found Error when tryes to open /app_dev.php

I had the same error, but I found out that the message was output when I typed app_dev.php/ but not when requesting app_dev.php (Notice the trailing slash /).

I think it has to do with the Router, but Its just an educated guess

Reference:

http://stackoverflow.com/questions/12424864/symfony-2-404-not-found-error-when-tryes-to-open-app-dev-php