Steps to Reproduce:
1. Open the wiki of The Document Foundation and login
2. Open Special:Preferences (個人設定 in Japanese)
Fatal exception of type MWException
can edit config...
Seems to be a bug in MediaWiki, filed as https://bugzilla.wikimedia.org/show_bug.cgi?id=42355
Changed the configuration in our wiki to make it work again.
(In reply to comment #1)
> Seems to be a bug in MediaWiki, filed as
> Changed the configuration in our wiki to make it work again.
Thanks for fixing this!