Request ID: W7bPjArAEHYAAC2B6EYAAABG
RuntimeException: Could not acquire lock for page ID '6548940'.
#0 /srv/mediawiki/php-1.32.0-wmf.24/includes/deferred/DeferredUpdates.php(268): LinksUpdate->doUpdate() #1 /srv/mediawiki/php-1.32.0-wmf.24/includes/deferred/DeferredUpdates.php(214): DeferredUpdates::runUpdate(LinksUpdate, Wikimedia\Rdbms\LBFactoryMulti, string, integer) #2 /srv/mediawiki/php-1.32.0-wmf.24/includes/deferred/DeferredUpdates.php(134): DeferredUpdates::execute(array, string, integer) #3 /srv/mediawiki/php-1.32.0-wmf.24/includes/MediaWiki.php(914): DeferredUpdates::doUpdates(string) #4 /srv/mediawiki/php-1.32.0-wmf.24/includes/MediaWiki.php(734): MediaWiki->restInPeace(string, boolean) #5 [internal function]: Closure$MediaWiki::doPostOutputShutdown()
When the same page is edited repeatedly in a short period of time, the LinksUpdate process can fail.
This particular exception was from edits at https://en.wikipedia.org/w/index.php?title=Wikipedia:Version_1.0_Editorial_Team/Biography_(military)_articles_by_quality_log&offset=20181005024213&action=history. Due to the high edit frequency there, the locks were unavailable and some of the edits had their update fail. When this happens for the "last" edit, which is not unlikely, it means the database will remain indefinitely in an incorrect state.
Derived data such as used by category membership, language links, WhatLinksHere, and search, may return outdated or incorrect information about the page in question, and does not automatically recover in an eventual way.
A similar issue was reported from RefreshLink jobs on the JobQueue as T170596, which we fixed. However, the issue still happens when multiple edits are made to the same page by the same or different users.