Hi there,
The MediaWiki 1.26 upgrade that was performed today has succeeded, but it took another hour longer for All The Tropes than expected (there already was a scheduled maintenance window of two hours, but ATT was read-only for three hours instead).
I'm sorry for that. When running update.php (that's a script we use for updating the database so it will work with extension/MediaWiki changes), I noticed it (likely, I couldn't find out whether it did or not) ran populateLogUsertext.php (that 'fixes' username log entries in Special:Log). Running populateLogUsertext.php could have a more or less catastrophic effect to Special:Log entries that were made before the move to Miraheze, with as result completely inaccurate log entries that could have been unrecoverable.
Since I didn't want to take any risk, I decided to restore a part of the backup we made just before updating MediaWiki. I know it's a pity the wiki was read-only for another hour, but I hope you understand why I chose for it.
-- Southparkfan, Miraheze System Administrator.