Please follow the below template, it will help us to help you!
Expected Behaviour:
Changes to DNS settings to be saved
Actual Behaviour:
Error message "Wrong token! Please re-login on the Pi-hole dashboard."
Note also this message on entry to settings menu...
"There was a problem applying your settings.
Debugging information:
PHP error (2): session_start(): Failed to read session data: files (path: /var/lib/php/sessions) in /var/www/html/admin/scripts/pi-hole/php/password.php:12 "