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
Query: SELECT rev_id,rev_page,rev_text_id,rev_timestamp,rev_comment,rev_user_text,rev_user,rev_minor_edit,rev_deleted,rev_len,rev_parent_id,rev_sha1,page_namespace,page_title,page_id,page_latest,user_name FROM `revision` INNER JOIN `page` ON ((page_id = rev_page)) LEFT JOIN `user` ON ((rev_user != 0) AND (user_id = rev_user)) WHERE rev_id = '625' LIMIT 1
Function: Revision::fetchFromConds
Error: 1927 Lost connection to backend server: connection closed by peer (server3: Generated event) (database_maxscale:4006)