A database error has occurred.  Did you forget to run maintenance/update.php after upgrading?  See: https://www.mediawiki.org/wiki/Manual:Upgrading#Run_the_update_script<br />
Query: DELETE FROM `l10n_cache` WHERE lc_lang = 'pl'<br />
Function: LCStore_DB::startWrite<br />
Error: 1213 Deadlock found when trying to get lock; try restarting transaction (localhost)<br />