This is the page displayed in the production environment when symfony catches an error.
Symfony looks for a error.html.php
file and let you choose where you prefer to put it:
At mySfProject/apps/frontend/config/error/error.html.php
Useful if you want to have a different version for each application
At mySfProject/config/error/error.html.php
The main configuration folder of your project
If you want, you can grab the original file and modify it.
Display the "Oops! An Error Occurred" page to test it
In an action that works fine, add on top:
throw new Exception('Only for test, don\'t forget to remove it!');
Test the related page in the production environement.