SQL-DATABASE ERROR

Database error in WoltLab Burning Board (): Link-ID == false, connect failed
mysql error:
mysql error number:
mysql version: unknown
php version: 7.0.33-0ubuntu0.16.04.16
Date: 08.05.2024 @ 17:07
Script: /board/register.php?sid=725726413de6deb612e6aeaea1c02a84
Referer: http://www.tabletop-tirol.net/board/register.php?sid=725726413de6deb612e6aeaea1c02a84