If upgrading from before 1.7, you may want to run refreshLinks.php to ensure
new database fields are filled with data.
+If upgrading from before 1.11, and you are using a wiki as a commons repository,
+make sure that it is updated as well. Otherwise, errors may arise due to
+database schema changes.
+
If you are upgrading from MediaWiki 1.4.x or earlier, some major database
changes are made, and there is a slightly higher chance that things could
break. Don't forget to always back up your database before upgrading!