Manual:UpdateCollation.php

This script updates category collations. You need to run this script after $wgCategoryCollation has been changed. It is also needed to be run after upgrading to 1.17 and later from a version of MediaWiki before 1.17. Normally it is run as part of Manual:update.php.

If your category collations are messed up (aka things sort incorrectly in categories), you can use the  switch to forcibly fix all the category collations. See  for a list of all options.