session_start(): Session data file is not created by your uid
PHP requires session file to be owned by the user running PHP.
Then just run
chown -R www-data:www-data /var/www/storage/sessions/ to own session folder and files by your PHP user (
www-data:www-data are your PHP user and group separated by
You can use PHP method
get_current_user() or run in bash
php -i | grep user and find your user running PHP there.
Editing config/config.yml and replacing save_path:
session: save_path: '/tmp'
this works for me:
sudo chown -R www-data:www-data /var/lib/php/sessions