Vérifiez que Symfony fonctionne correctement

Bonjour,
quand je met cette adressee :
http://localhost/Symfony2/web/config.php

j'ai ce probleme dans une page !

Configuration Checker
This script analyzes your system to check whether is ready to run Symfony applications.
RECOMMENDATIONS
To enhance your Symfony experience, it’s recommended that you fix the following:
intl ICU version installed on your system (56.1) should match the ICU data bundled with Symfony (55.1)
In most cases you should be fine, but please verify there is no inconsistencies between data provided by Symfony and the intl extension. See https://github.com/symfony/symfony/issues/15007 for an example of inconsistencies you might run into.
a PHP accelerator should be installed
Install and/or enable a PHP accelerator (highly recommended).
Re-check configuration