Argument 3 passed to Wikibase\Lib\Store\CachingFallbackLabelDescriptionLookup::buildCacheKey() must be of the type string, null given, called in /srv/mediawiki/php-1.36.0-wmf.3/extensions/Wikibase/lib/includes/Store/CachingFallbackLabelDescriptionLookup.php on line 119
A couple of these shortly after rolling 1.36.0-wmf.3 to group1. Not yet treating as a blocker for T257971, but monitoring.
#0 /srv/mediawiki/php-1.36.0-wmf.3/extensions/Wikibase/lib/includes/Store/CachingFallbackLabelDescriptionLookup.php(119): Wikibase\Lib\Store\CachingFallbackLabelDescriptionLookup->buildCacheKey(Wikibase\DataModel\Entity\ItemId, integer, NULL, string)
#1 /srv/mediawiki/php-1.36.0-wmf.3/extensions/Wikibase/lib/includes/Store/CachingFallbackLabelDescriptionLookup.php(106): Wikibase\Lib\Store\CachingFallbackLabelDescriptionLookup->getTerm(Wikibase\DataModel\Entity\ItemId, NULL, string)
#2 /srv/mediawiki/php-1.36.0-wmf.3/extensions/Wikibase/client/includes/Usage/UsageTrackingLanguageFallbackLabelDescriptionLookup.php(71): Wikibase\Lib\Store\CachingFallbackLabelDescriptionLookup->getLabel(Wikibase\DataModel\Entity\ItemId)
#3 /srv/mediawiki/php-1.36.0-wmf.3/extensions/Wikibase/client/includes/DataAccess/Scribunto/WikibaseLanguageDependentLuaBindings.php(60): Wikibase\Client\Usage\UsageTrackingLanguageFallbackLabelDescriptionLookup->getLabel(Wikibase\DataModel\Entity\ItemId)
#4 /srv/mediawiki/php-1.36.0-wmf.3/extensions/Wikibase/client/includes/DataAccess/Scribunto/Scribunto_LuaWikibaseLibrary.php(606): Wikibase\Client\DataAccess\Scribunto\WikibaseLanguageDependentLuaBindings->getLabel(string)
#5 /srv/mediawiki/php-1.36.0-wmf.3/extensions/Scribunto/includes/engines/LuaSandbox/LuaSandboxCallback.php(26): Wikibase\Client\DataAccess\Scribunto\Scribunto_LuaWikibaseLibrary->getLabel(string)
#6 [internal function]: Scribunto_LuaSandboxCallback->__call(string, array)
#7 /srv/mediawiki/php-1.36.0-wmf.3/extensions/Scribunto/includes/engines/LuaSandbox/LuaSandboxInterpreter.php(113): LuaSandboxFunction->call(LuaSandboxFunction)
#8 /srv/mediawiki/php-1.36.0-wmf.3/extensions/Scribunto/includes/engines/LuaCommon/LuaEngine.php(291): Scribunto_LuaSandboxInterpreter->callFunction(LuaSandboxFunction, LuaSandboxFunction)
#9 /srv/mediawiki/php-1.36.0-wmf.3/extensions/Scribunto/includes/engines/LuaCommon/LuaModule.php(68): Scribunto_LuaEngine->executeFunctionChunk(LuaSandboxFunction, PPTemplateFrame_Hash)
#10 /srv/mediawiki/php-1.36.0-wmf.3/extensions/Scribunto/includes/common/Hooks.php(128): Scribunto_LuaModule->invoke(string, PPTemplateFrame_Hash)
#11 /srv/mediawiki/php-1.36.0-wmf.3/includes/parser/Parser.php(3340): ScribuntoHooks::invokeHook(Parser, PPTemplateFrame_Hash, array)
#12 /srv/mediawiki/php-1.36.0-wmf.3/includes/parser/Parser.php(3047): Parser->callParserFunction(PPTemplateFrame_Hash, string, array)
#13 /srv/mediawiki/php-1.36.0-wmf.3/includes/parser/PPFrame_Hash.php(253): Parser->braceSubstitution(array, PPTemplateFrame_Hash)
#14 /srv/mediawiki/php-1.36.0-wmf.3/extensions/ParserFunctions/includes/ParserFunctions.php(144): PPFrame_Hash->expand(PPNode_Hash_Tree)
#15 /srv/mediawiki/php-1.36.0-wmf.3/includes/parser/Parser.php(3340): MediaWiki\Extensions\ParserFunctions\ParserFunctions::ifeq(Parser, PPTemplateFrame_Hash, array)
#16 /srv/mediawiki/php-1.36.0-wmf.3/includes/parser/Parser.php(3047): Parser->callParserFunction(PPTemplateFrame_Hash, string, array)
#17 /srv/mediawiki/php-1.36.0-wmf.3/includes/parser/PPFrame_Hash.php(253): Parser->braceSubstitution(array, PPTemplateFrame_Hash)
#18 /srv/mediawiki/php-1.36.0-wmf.3/includes/parser/Parser.php(3225): PPFrame_Hash->expand(PPNode_Hash_Tree)
#19 /srv/mediawiki/php-1.36.0-wmf.3/includes/parser/PPFrame_Hash.php(253): Parser->braceSubstitution(array, PPTemplateFrame_Hash)
#20 /srv/mediawiki/php-1.36.0-wmf.3/includes/parser/PPTemplateFrame_Hash.php(89): PPFrame_Hash->expand(PPNode_Hash_Tree, integer)
#21 /srv/mediawiki/php-1.36.0-wmf.3/includes/parser/Parser.php(3222): PPTemplateFrame_Hash->cachedExpand(string, PPNode_Hash_Tree)
#22 /srv/mediawiki/php-1.36.0-wmf.3/includes/parser/PPFrame_Hash.php(253): Parser->braceSubstitution(array, PPFrame_Hash)
#23 /srv/mediawiki/php-1.36.0-wmf.3/includes/parser/Parser.php(2887): PPFrame_Hash->expand(PPNode_Hash_Tree, integer)
#24 /srv/mediawiki/php-1.36.0-wmf.3/includes/parser/Parser.php(1556): Parser->replaceVariables(string)
#25 /srv/mediawiki/php-1.36.0-wmf.3/includes/parser/Parser.php(651): Parser->internalParse(string)
#26 /srv/mediawiki/php-1.36.0-wmf.3/includes/content/WikitextContent.php(374): Parser->parse(string, Title, ParserOptions, boolean, boolean, integer)
#27 /srv/mediawiki/php-1.36.0-wmf.3/includes/content/AbstractContent.php(590): WikitextContent->fillParserOutput(Title, integer, ParserOptions, boolean, ParserOutput)
#28 /srv/mediawiki/php-1.36.0-wmf.3/includes/Revision/RenderedRevision.php(266): AbstractContent->getParserOutput(Title, integer, ParserOptions, boolean)
#29 /srv/mediawiki/php-1.36.0-wmf.3/includes/Revision/RenderedRevision.php(235): MediaWiki\Revision\RenderedRevision->getSlotParserOutputUncached(WikitextContent, boolean)
#30 /srv/mediawiki/php-1.36.0-wmf.3/includes/Revision/RevisionRenderer.php(215): MediaWiki\Revision\RenderedRevision->getSlotParserOutput(string)
#31 /srv/mediawiki/php-1.36.0-wmf.3/includes/Revision/RevisionRenderer.php(152): MediaWiki\Revision\RevisionRenderer->combineSlotOutput(MediaWiki\Revision\RenderedRevision, array)
#32 [internal function]: MediaWiki\Revision\RevisionRenderer->MediaWiki\Revision\{closure}(MediaWiki\Revision\RenderedRevision, array)
#33 /srv/mediawiki/php-1.36.0-wmf.3/includes/Revision/RenderedRevision.php(197): call_user_func(Closure, MediaWiki\Revision\RenderedRevision, array)
#34 /srv/mediawiki/php-1.36.0-wmf.3/includes/poolcounter/PoolWorkArticleView.php(216): MediaWiki\Revision\RenderedRevision->getRevisionParserOutput()
#35 /srv/mediawiki/php-1.36.0-wmf.3/includes/poolcounter/PoolCounterWork.php(162): PoolWorkArticleView->doWork()
#36 /srv/mediawiki/php-1.36.0-wmf.3/includes/page/Article.php(811): PoolCounterWork->execute()
#37 /srv/mediawiki/php-1.36.0-wmf.3/includes/page/CategoryPage.php(63): Article->view()
#38 /srv/mediawiki/php-1.36.0-wmf.3/includes/actions/ViewAction.php(74): CategoryPage->view()
#39 /srv/mediawiki/php-1.36.0-wmf.3/includes/MediaWiki.php(527): ViewAction->show()
#40 /srv/mediawiki/php-1.36.0-wmf.3/includes/MediaWiki.php(313): MediaWiki->performAction(CategoryTreeCategoryPage, Title)
#41 /srv/mediawiki/php-1.36.0-wmf.3/includes/MediaWiki.php(940): MediaWiki->performRequest()
#42 /srv/mediawiki/php-1.36.0-wmf.3/includes/MediaWiki.php(543): MediaWiki->main()
#43 /srv/mediawiki/php-1.36.0-wmf.3/index.php(53): MediaWiki->run()
#44 /srv/mediawiki/php-1.36.0-wmf.3/index.php(46): wfIndexMain()
#45 /srv/mediawiki/w/index.php(3): require(string)
#46 {main}Since we're already rolled back due to T259745, I'm going to err on the side of marking this a blocker until triaged.
Adding @Pablo-WMDE as this week's IM and @Addshore and @Michael who touched the code recently.
This is actually the exact same root cause as in T259745: The language fallback chain in question is empty, and calling $languageCode = $languageCodes[0] on an empty array results in the language code being null.
https://gerrit.wikimedia.org/r/c/mediawiki/extensions/Wikibase/+/608628 is indeed what caused this, specifically https://gerrit.wikimedia.org/r/c/mediawiki/extensions/Wikibase/+/608628/13/lib/includes/TermLanguageFallbackChain.php. I created T259779 to keep track of the common root cause.
Change 618703 had a related patch set uploaded (by Thiemo Kreuz (WMDE); owner: Thiemo Kreuz (WMDE)):
[mediawiki/extensions/Wikibase@master] Fix CachingFallbackLabelDescriptionLookup failing in edge-cases
We discussed this task during the Wikidata-Campsite daily and it will be addressed with high priority.
There is a patch up already which has some red because of another problem (T258184) which is in the making as well.
Change 618579 had a related patch set uploaded (by Ladsgroup; owner: Thiemo Kreuz (WMDE)):
[mediawiki/extensions/Wikibase@wmf/1.36.0-wmf.3] Fix CachingFallbackLabelDescriptionLookup failing in edge-cases
Change 618579 merged by Lucas Werkmeister (WMDE):
[mediawiki/extensions/Wikibase@wmf/1.36.0-wmf.3] Fix CachingFallbackLabelDescriptionLookup failing in edge-cases
Mentioned in SAL (#wikimedia-operations) [2020-08-06T11:27:17Z] <lucaswerkmeister-wmde@deploy1001> Synchronized php-1.36.0-wmf.3/extensions/Wikibase/lib/: Backport: [[gerrit:618579|Fix CachingFallbackLabelDescriptionLookup failing in edge-cases (T259744)]] (duration: 01m 10s)
This should be fixed on wmf.3 now, but not yet on master. Marking as wmf.4 deployment blocker so we don’t forget about it.
Removing as wmf.3 blocker since it’s fixed on that branch, and lowering priority for the same reason.
Change 618703 merged by jenkins-bot:
[mediawiki/extensions/Wikibase@master] Fix CachingFallbackLabelDescriptionLookup failing in edge-cases