SQL-DATABASE ERROR

Database error in WoltLab Burning Board (2.3.6): Link-ID == false, connect failed
mysql error: Too many connections
mysql error number: 1040
mysql version: unknown
php version: 5.2.17
Date: 13.11.2018 @ 03:20
Script: /calendar.php?action=eventcalendar&sid=8f672786b151aca4628b8dc8576af6f9
Referer: