I followed a random link on twitter[1] where someone alleged[2] that the MediaWiki updater tries to update databases with names that are no longer allowed, and doesn't warn about that before updating.

This was the report:

Anyone here really good with mediawiki? I recently upgraded two installations to 1.20 from 1.13.4, ran the update.php and all was fine except uploads don’t work anymore. (Could not create directory “mwstore://local-backend/local-public/3/37″). It’s not the owner/permissions on /images or children but something more subtle that seems (seems) to involve the mwstore://local-backend part not being translated into a filesystem path. With my primitive debugging it looks like it’s giving that path straight to mkdir. I’ve done the Google and short of trying to wrap my head around the mediawiki codebase I’m out of ideas, I guess.

Follow-up:

Problem solved. Turns out the new database backend thing in mediawiki doesn’t like database names with dots in them, and doesn’t tell you. Thank you Florian Holzhauer for finding it!

[1] https://twitter.com/rop_g/statuses/324983132988264448
[2] http://rop.gonggri.jp/?p=695

Adding a scenario which will allow us to reproduce this issue (or someone who can confirm it), may help in preventing other wiki administrators avoid this issue.

Version: 1.20.x
Severity: normal