how to fix Symfony CSRF token is invalid. Please try to resubmit the form

If you have problems with uploading files, you should not disable  CSRF, only fix it with this hints:

* make sure in php.ini (in all directories in /etc/php5/) max_post_size much bigger than upload_size.
* do not forget to restart server (apache or nginx) and "service php5-fpm restart"