Found in Logstash:
> PHP Error: Argument 1 passed to WikibaseQuality\ConstraintReport\Api\ResultsCache::delete() must be an instance of Wikibase\DataModel\Entity\EntityId, null given
>
> #0 /srv/mediawiki/php-1.31.0-wmf.27/extensions/WikibaseQualityConstraints/src/Api/ResultsCache.php(85): MWExceptionHandler::handleError(integer, string, string, integer, array, array)
> #1 /srv/mediawiki/php-1.31.0-wmf.27/extensions/WikibaseQualityConstraints/src/WikibaseQualityConstraintsHooks.php(80): WikibaseQuality\ConstraintReport\Api\ResultsCache->delete(NULL)
> #2 /srv/mediawiki/php-1.31.0-wmf.27/includes/Hooks.php(177): WikibaseQuality\ConstraintReport\WikibaseQualityConstraintsHooks::onArticlePurge(WikiPage)
> #3 /srv/mediawiki/php-1.31.0-wmf.27/includes/Hooks.php(205): Hooks::callHook(string, array, array, NULL)
> #4 /srv/mediawiki/php-1.31.0-wmf.27/includes/page/WikiPage.php(1171): Hooks::run(string, array)
> #5 /srv/mediawiki/php-1.31.0-wmf.27/includes/page/Article.php(2133): WikiPage->doPurge()
> #6 /srv/mediawiki/php-1.31.0-wmf.27/includes/actions/PurgeAction.php(45): Article->doPurge()
> #7 /srv/mediawiki/php-1.31.0-wmf.27/includes/actions/PurgeAction.php(66): PurgeAction->onSubmit(array)
> #8 /srv/mediawiki/php-1.31.0-wmf.27/includes/MediaWiki.php(500): PurgeAction->show()
> #9 /srv/mediawiki/php-1.31.0-wmf.27/includes/MediaWiki.php(294): MediaWiki->performAction(Article, Title)
> #10 /srv/mediawiki/php-1.31.0-wmf.27/includes/MediaWiki.php(861): MediaWiki->performRequest()
> #11 /srv/mediawiki/php-1.31.0-wmf.27/includes/MediaWiki.php(524): MediaWiki->main()
> #12 /srv/mediawiki/php-1.31.0-wmf.27/index.php(42): MediaWiki->run()
> #13 /srv/mediawiki/w/index.php(3): include(string)
> #14 {main}
Only happened once in the past 24 hours. Request URL indicates someone was purging an item (let’s redact which one it was, it probably doesn’t matter), which might explain why it’s not a frequent error.