If you are getting this message, then VaultWiki was still installed in the database backup you used to migrate. You need to use another backup from AFTER VaultWiki was removed, or you need to upload the VaultWiki files to your new server, or you need to disable plugins globally in vBulletin's
includes/config.php file, by adding:
Code:
define('DISABLE_HOOKS', true);
That would give you access to the AdminCP again so that you can uninstall VaultWiki.