SQL-DATABASE ERROR

Database error in WoltLab Burning Board (): Link-ID == false, connect failed
mysql error: Too many connections
mysql error number: 1040
mysql version: unknown
php version: 5.6.36-1+0~20180505045733.13+jessie~1.gbp9b5cab
Date: 25.05.2018 @ 05:27
Script: /register.php?sid=905036be8b498a76a4d70a6210fb4954
Referer: