```
2020-01-10 08:32:52 [Xhg2swpAAEwAABi@BYMAAAEL] mw1281 zhwiki 1.35.0-wmf.14 exception ERROR: [Xhg2swpAAEwAABi@BYMAAAEL] /w/api.php?format=json&formatversion=2&errorformat=plaintext&action=query&redirects=&converttitles=&prop=extracts|pageimages|pageprops&exsentences=5&piprop=thumbnail|name&pilicense=any&explaintext=&pithumbsize=320&titles=%E5%A4%8F%E6%B3%A2%E5%B8%9D%E8%AB%B8%E5%B3%B6&uselang=zh-hant LogicException from line 421 of /srv/mediawiki/php-1.35.0-wmf.14/extensions/Cite/src/ReferenceStack.php: Unknown ref "BLUE" in group "" {"exception_id":"Xhg2swpAAEwAABi@BYMAAAEL","exception_url":"/w/api.php?format=json&formatversion=2&errorformat=plaintext&action=query&redirects=&converttitles=&prop=extracts|pageimages|pageprops&exsentences=5&piprop=thumbnail|name&pilicense=any&explaintext=&pithumbsize=320&titles=%E5%A4%8F%E6%B3%A2%E5%B8%9D%E8%AB%B8%E5%B3%B6&uselang=zh-hant","caught_by":"mwe_handler"}
[Exception LogicException] (/srv/mediawiki/php-1.35.0-wmf.14/extensions/Cite/src/ReferenceStack.php:421) Unknown ref "BLUE" in group ""
#0 /srv/mediawiki/php-1.35.0-wmf.14/extensions/Cite/src/Cite.php(333): Cite\ReferenceStack->appendText(string, string, string)
#1 /srv/mediawiki/php-1.35.0-wmf.14/extensions/Cite/src/Cite.php(454): Cite\Cite->guardedRef(Parser, string, array)
#2 /srv/mediawiki/php-1.35.0-wmf.14/extensions/Cite/src/Cite.php(413): Cite\Cite->guardedReferences(string, array, Parser)
#3 /srv/mediawiki/php-1.35.0-wmf.14/extensions/Cite/src/Hooks/CiteParserTagHooks.php(63): Cite\Cite->references(string, array, Parser)
#4 /srv/mediawiki/php-1.35.0-wmf.14/includes/parser/Parser.php(4046): Cite\Hooks\CiteParserTagHooks::references(string, array, Parser, PPTemplateFrame_Hash)
#5 /srv/mediawiki/php-1.35.0-wmf.14/includes/parser/CoreParserFunctions.php(1111): Parser->extensionSubstitution(array, PPTemplateFrame_Hash)
#6 /srv/mediawiki/php-1.35.0-wmf.14/includes/parser/Parser.php(3569): CoreParserFunctions::tagObj(Parser, PPTemplateFrame_Hash, array)
#7 /srv/mediawiki/php-1.35.0-wmf.14/includes/parser/Parser.php(3273): Parser->callParserFunction(PPTemplateFrame_Hash, string, array)
#8 /srv/mediawiki/php-1.35.0-wmf.14/includes/parser/PPFrame_Hash.php(253): Parser->braceSubstitution(array, PPTemplateFrame_Hash)
#9 /srv/mediawiki/php-1.35.0-wmf.14/includes/parser/Parser.php(3451): PPFrame_Hash->expand(PPNode_Hash_Tree)
#10 /srv/mediawiki/php-1.35.0-wmf.14/includes/parser/PPFrame_Hash.php(253): Parser->braceSubstitution(array, PPFrame_Hash)
#11 /srv/mediawiki/php-1.35.0-wmf.14/includes/parser/Parser.php(3115): PPFrame_Hash->expand(PPNode_Hash_Tree, integer)
#12 /srv/mediawiki/php-1.35.0-wmf.14/includes/parser/Parser.php(1478): Parser->replaceVariables(string)
#13 /srv/mediawiki/php-1.35.0-wmf.14/includes/parser/Parser.php(586): Parser->internalParse(string)
#14 /srv/mediawiki/php-1.35.0-wmf.14/includes/content/WikitextContent.php(368): Parser->parse(string, Title, ParserOptions, boolean, boolean, integer)
#15 /srv/mediawiki/php-1.35.0-wmf.14/includes/content/AbstractContent.php(555): WikitextContent->fillParserOutput(Title, integer, ParserOptions, boolean, ParserOutput)
#16 /srv/mediawiki/php-1.35.0-wmf.14/includes/Revision/RenderedRevision.php(267): AbstractContent->getParserOutput(Title, integer, ParserOptions, boolean)
#17 /srv/mediawiki/php-1.35.0-wmf.14/includes/Revision/RenderedRevision.php(236): MediaWiki\Revision\RenderedRevision->getSlotParserOutputUncached(WikitextContent, boolean)
#18 /srv/mediawiki/php-1.35.0-wmf.14/includes/Revision/RevisionRenderer.php(215): MediaWiki\Revision\RenderedRevision->getSlotParserOutput(string)
#19 /srv/mediawiki/php-1.35.0-wmf.14/includes/Revision/RevisionRenderer.php(152): MediaWiki\Revision\RevisionRenderer->combineSlotOutput(MediaWiki\Revision\RenderedRevision, array)
#20 [internal function]: MediaWiki\Revision\RevisionRenderer->MediaWiki\Revision\{closure}(MediaWiki\Revision\RenderedRevision, array)
#21 /srv/mediawiki/php-1.35.0-wmf.14/includes/Revision/RenderedRevision.php(198): call_user_func(Closure, MediaWiki\Revision\RenderedRevision, array)
#22 /srv/mediawiki/php-1.35.0-wmf.14/includes/poolcounter/PoolWorkArticleView.php(196): MediaWiki\Revision\RenderedRevision->getRevisionParserOutput()
#23 /srv/mediawiki/php-1.35.0-wmf.14/includes/poolcounter/PoolCounterWork.php(125): PoolWorkArticleView->doWork()
#24 /srv/mediawiki/php-1.35.0-wmf.14/includes/page/WikiPage.php(1263): PoolCounterWork->execute()
#25 /srv/mediawiki/php-1.35.0-wmf.14/includes/api/ApiParse.php(600): WikiPage->getParserOutput(ParserOptions, integer, boolean)
#26 /srv/mediawiki/php-1.35.0-wmf.14/includes/api/ApiParse.php(165): ApiParse->getParsedContent(WikiPage, ParserOptions, boolean, NULL, NULL, boolean)
#27 /srv/mediawiki/php-1.35.0-wmf.14/includes/api/ApiMain.php(1603): ApiParse->execute()
#28 /srv/mediawiki/php-1.35.0-wmf.14/includes/api/ApiMain.php(508): ApiMain->executeAction()
#29 /srv/mediawiki/php-1.35.0-wmf.14/extensions/TextExtracts/includes/ApiQueryExtracts.php(235): ApiMain->execute()
#30 /srv/mediawiki/php-1.35.0-wmf.14/extensions/TextExtracts/includes/ApiQueryExtracts.php(159): TextExtracts\ApiQueryExtracts->parse(WikiPage)
#31 /srv/mediawiki/php-1.35.0-wmf.14/extensions/TextExtracts/includes/ApiQueryExtracts.php(96): TextExtracts\ApiQueryExtracts->getExtract(Title)
#32 /srv/mediawiki/php-1.35.0-wmf.14/includes/api/ApiQuery.php(255): TextExtracts\ApiQueryExtracts->execute()
#33 /srv/mediawiki/php-1.35.0-wmf.14/includes/api/ApiMain.php(1603): ApiQuery->execute()
#34 /srv/mediawiki/php-1.35.0-wmf.14/includes/api/ApiMain.php(539): ApiMain->executeAction()
#35 /srv/mediawiki/php-1.35.0-wmf.14/includes/api/ApiMain.php(510): ApiMain->executeActionWithErrorHandling()
#36 /srv/mediawiki/php-1.35.0-wmf.14/api.php(78): ApiMain->execute()
#37 /srv/mediawiki/w/api.php(3): require(string)
#38 {main}
```