go to http://en.wikipedia.beta.wmflabs.org/w/api.php
error is
PHP fatal error in /srv/common-local/php-master/includes/api/ApiQueryBase.php line 43:
Argument 1 passed to ApiQueryBase::__construct() must be an instance of ApiQuery, instance of ApiMain given, called in /srv/common-local/php-master/extensions/SiteMatrix/SiteMatrixApi.php on line 15 and defined
Version: unspecified
Severity: major