Thread:Project:Support desk/"" is not a valid magic word for "speciale"

Since I have upgraded from 1.19.1 to 1.20.2 I always get the following errors in the apache logs: The page never is shown - instead I only get a blank page.
 * "" is not a valid magic word for "speciale"
 * PHP Warning: array_map: An error occurred while invoking the map callback in /var/www/wiki/mediawiki-1.20.2/includes/Title.php on line 2087
 * PHP Fatal error: Call to a member function matchStartAndRemove on a non-object in /var/www/wiki/mediawiki-1.20.2/includes/parser/Parser.php on line 3147

php --version PHP 5.3.3-7+squeeze14 with Suhosin-Patch (cli) (built: Aug 6 2012 14:18:06) Copyright (c) 1997-2009 The PHP Group Zend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies with Suhosin v0.9.32.1, Copyright (c) 2007-2010, by SektionEins GmbH mysql --version mysql Ver 14.14 Distrib 5.1.63, for debian-linux-gnu (x86_64) using readline 6.1