Manual:DBError.php

MediaWiki file: DBError.php
Location:	includes/libs/rdbms/exception/
Source code:	master • 1.42.3 • 1.41.4 • 1.39.10
Classes:	Wikimedia\Rdbms\DBError

DBConnectionError

This is the infamous error:

Undskyld! Siden har tekniske problemer. Prøv at vente et par minutter og opdater så siden igen.

If you see this, the database is very unhappy, but at least MediaWiki is still alive and knows about it.

Kan ikke forbinde til database

I haven't solved this for myself yet, but you should look into it following the same way I did.

1. Check out the apache2 error log. If you're on ubuntu this was at "/var/log/apache2/error.log" by default when I wrote this.
2. In my case, I got the following error .... "MySQL server has gone away in" .... followed by .... Error reading result set's header in ......
3. This was supposedly caused by connection problems. Search those two terms and you should see several different places where people address it. Good luck!