To the tester I'm really sorry. This change involves a few new sql statements and will need to be tested on all supported databases. Load the test.php file into your moodle directory and run it. If you have a look at your tag_instance table you should see that you now have about 9000 entries. If you want to test this before using the patch, then make sure to comment out the following (tag/lib.php tag_delete_instance()): // Trigger tag removed event. $event = \core\event\tag_removed::create(array( 'objectid' => $taginstance->id, 'contextid' => $taginstance->contextid, 'other' => array( 'tagid' => $tag->id, 'tagname' => $tag->name, 'tagrawname' => $tag->rawname, 'itemid' => $taginstance->itemid, 'itemtype' => $taginstance->itemtype ) )); $event->add_record_snapshot('tag_instance', $taginstance); $event->trigger(); This code will fail if the tag name and tag rawname are not provided, which can not be provided when the tag has already been deleted. This is part of the code that we are testing. This is fixed in the patch. Run the following cron task: php admin/tool/task/cli/schedule_task.php --execute=\\core\\task tag_cron_task Note that the used dbqueries amount is around 220 (if you have around 9000 tag_instance entries) which is reduced from the previous figure of around 46000.