Warning: session_start(): Session data file is not created by your uid in

PHP requires a session file to be owned by the user running PHP.

Then just run chown -R www-data:www-data /var/www/storage/session/ to own session folder and files by your PHP user (www-data:www-data are your PHP user and group separated by :).

sudo chown -R www-data:www-data /var/lib/php/session
or
sudo chown -R apache:apache /var/lib/php/session