I have a running MediaWiki with the global $wgLanguageCode = "de". When a user changes his language, to lets say 'en', the user interface is still in 'de'. How can that be?
The database also has the changed setting 'en' set. The query I use is
SELECT up_user as `User`, convert(up_value using UTF8) as `Language` FROM wiki.user_properties where up_property = 'language';
So I guess its a bug?