Internal error

From Embryology

[ZfkdX-BBDdjyhozFYPz8CQAAAMA] /embryology/index.php/Endocrine_-_Thymus_Development Exception: preg_match_all error 4: Malformed UTF-8 characters, possibly incorrectly encoded

Backtrace:

from /var/www/html/embryology/includes/MagicWordArray.php(319)
#0 /var/www/html/embryology/includes/parser/Parser.php(4110): MagicWordArray->matchAndRemove()
#1 /var/www/html/embryology/includes/parser/Parser.php(1635): Parser->handleDoubleUnderscore()
#2 /var/www/html/embryology/includes/parser/Parser.php(881): Parser->internalParse()
#3 /var/www/html/embryology/extensions/Cite/src/ReferencesFormatter.php(73): Parser->recursiveTagParse()
#4 /var/www/html/embryology/extensions/Cite/src/Cite.php(499): Cite\ReferencesFormatter->formatReferences()
#5 /var/www/html/embryology/extensions/Cite/src/Cite.php(471): Cite\Cite->formatReferences()
#6 /var/www/html/embryology/extensions/Cite/src/Cite.php(418): Cite\Cite->guardedReferences()
#7 /var/www/html/embryology/extensions/Cite/src/Hooks/CiteParserTagHooks.php(72): Cite\Cite->references()
#8 /var/www/html/embryology/includes/parser/Parser.php(4017): Cite\Hooks\CiteParserTagHooks::references()
#9 /var/www/html/embryology/includes/parser/PPFrame_Hash.php(353): Parser->extensionSubstitution()
#10 /var/www/html/embryology/includes/parser/Parser.php(2951): PPFrame_Hash->expand()
#11 /var/www/html/embryology/includes/parser/Parser.php(1609): Parser->replaceVariables()
#12 /var/www/html/embryology/includes/parser/Parser.php(723): Parser->internalParse()
#13 /var/www/html/embryology/includes/content/WikitextContentHandler.php(301): Parser->parse()
#14 /var/www/html/embryology/includes/content/ContentHandler.php(1721): WikitextContentHandler->fillParserOutput()
#15 /var/www/html/embryology/includes/content/Renderer/ContentRenderer.php(47): ContentHandler->getParserOutput()
#16 /var/www/html/embryology/includes/Revision/RenderedRevision.php(266): MediaWiki\Content\Renderer\ContentRenderer->getParserOutput()
#17 /var/www/html/embryology/includes/Revision/RenderedRevision.php(237): MediaWiki\Revision\RenderedRevision->getSlotParserOutputUncached()
#18 /var/www/html/embryology/includes/Revision/RevisionRenderer.php(221): MediaWiki\Revision\RenderedRevision->getSlotParserOutput()
#19 /var/www/html/embryology/includes/Revision/RevisionRenderer.php(158): MediaWiki\Revision\RevisionRenderer->combineSlotOutput()
#20 [internal function]: MediaWiki\Revision\RevisionRenderer->MediaWiki\Revision\{closure}()
#21 /var/www/html/embryology/includes/Revision/RenderedRevision.php(199): call_user_func()
#22 /var/www/html/embryology/includes/poolcounter/PoolWorkArticleView.php(91): MediaWiki\Revision\RenderedRevision->getRevisionParserOutput()
#23 /var/www/html/embryology/includes/poolcounter/PoolWorkArticleViewCurrent.php(97): PoolWorkArticleView->renderRevision()
#24 /var/www/html/embryology/includes/poolcounter/PoolCounterWork.php(162): PoolWorkArticleViewCurrent->doWork()
#25 /var/www/html/embryology/includes/page/ParserOutputAccess.php(299): PoolCounterWork->execute()
#26 /var/www/html/embryology/includes/page/Article.php(714): MediaWiki\Page\ParserOutputAccess->getParserOutput()
#27 /var/www/html/embryology/includes/page/Article.php(528): Article->generateContentOutput()
#28 /var/www/html/embryology/includes/actions/ViewAction.php(78): Article->view()
#29 /var/www/html/embryology/includes/MediaWiki.php(542): ViewAction->show()
#30 /var/www/html/embryology/includes/MediaWiki.php(322): MediaWiki->performAction()
#31 /var/www/html/embryology/includes/MediaWiki.php(904): MediaWiki->performRequest()
#32 /var/www/html/embryology/includes/MediaWiki.php(562): MediaWiki->main()
#33 /var/www/html/embryology/index.php(50): MediaWiki->run()
#34 /var/www/html/embryology/index.php(46): wfIndexMain()
#35 {main}