If you get this problem: Symfony 3 The CSRF token is invalid. Please try to resubmit the form

Solution 1 :

In your app/config/config.yml

change : save_path: "%kernel.root_dir%/../var/sessions/%kernel.environment%"
to : save_path: ~

Solution 2 :

Givive permissions :

mkdir -p var/sessions
chmod 755 var/sessions