SQL-DATABASE ERROR

Database error in WoltLab Burning Board (): Link-ID == false, connect failed
mysql error: The server requested authentication method unknown to the client
mysql error number: 2054
mysql version: unknown
php version: 5.5.38
Date: 25.09.2016 @ 02:12
Script: /wbb2/thread.php?postid=11351
Referer: