SQL-DATABASE ERROR

Database error in (): Link-ID == false, connect failed
mysql error:
mysql error number:
mysql version: unknown
php version: 7.4.33
Date: 03.06.2024 @ 04:36
Script: /wbb2/calendar.php?sid=203a2ac47e4d921f09c0aaaf8ac35573
Referer: http://www.friendsbistro.de/wbb2/calendar.php?sid=203a2ac47e4d921f09c0aaaf8ac35573