Unable to connect to database.

A database error occurred while processing this request.
Catchable fatal error: Argument 1 passed to ConfigStore::__construct() must be an instance of Database, null given, called in /customers/8/1/b/adenauer-gymnasium.de/httpd.www/updates/concrete5.4.2.2/concrete/models/config.php on line 48 and defined in /customers/8/1/b/adenauer-gymnasium.de/httpd.www/updates/concrete5.4.2.2/concrete/models/config.php on line 136