MediaWiki internal error.

Original exception: [44e7571c39d01946d583a4b2] /index.php/Talk:Main_Page MWUnknownContentModelException: The content model 'flow-board' is not registered on this wiki.
See https://www.mediawiki.org/wiki/Content_handlers to find out which extensions handle this content model.
Backtrace:
from /store/wikidoc/mediawiki-1.40.0/includes/content/ContentHandlerFactory.php(203)
#0 /store/wikidoc/mediawiki-1.40.0/includes/content/ContentHandlerFactory.php(273): MediaWiki\Content\ContentHandlerFactory->validateContentHandler()
#1 /store/wikidoc/mediawiki-1.40.0/includes/content/ContentHandlerFactory.php(191): MediaWiki\Content\ContentHandlerFactory->createContentHandlerFromHook()
#2 /store/wikidoc/mediawiki-1.40.0/includes/content/ContentHandlerFactory.php(97): MediaWiki\Content\ContentHandlerFactory->createForModelID()
#3 /store/wikidoc/mediawiki-1.40.0/includes/page/WikiPage.php(311): MediaWiki\Content\ContentHandlerFactory->getContentHandler()
#4 /store/wikidoc/mediawiki-1.40.0/includes/MediaWiki.php(448): WikiPage->getContentHandler()
#5 /store/wikidoc/mediawiki-1.40.0/includes/MediaWiki.php(331): MediaWiki->initializeArticle()
#6 /store/wikidoc/mediawiki-1.40.0/includes/MediaWiki.php(923): MediaWiki->performRequest()
#7 /store/wikidoc/mediawiki-1.40.0/includes/MediaWiki.php(576): MediaWiki->main()
#8 /store/wikidoc/mediawiki-1.40.0/index.php(50): MediaWiki->run()
#9 /store/wikidoc/mediawiki-1.40.0/index.php(46): wfIndexMain()
#10 {main}

Exception caught inside exception handler: [44e7571c39d01946d583a4b2] /index.php/Talk:Main_Page MWUnknownContentModelException: The content model 'flow-board' is not registered on this wiki.
See https://www.mediawiki.org/wiki/Content_handlers to find out which extensions handle this content model.
Backtrace:
from /store/wikidoc/mediawiki-1.40.0/includes/content/ContentHandlerFactory.php(203)
#0 /store/wikidoc/mediawiki-1.40.0/includes/content/ContentHandlerFactory.php(273): MediaWiki\Content\ContentHandlerFactory->validateContentHandler()
#1 /store/wikidoc/mediawiki-1.40.0/includes/content/ContentHandlerFactory.php(191): MediaWiki\Content\ContentHandlerFactory->createContentHandlerFromHook()
#2 /store/wikidoc/mediawiki-1.40.0/includes/content/ContentHandlerFactory.php(97): MediaWiki\Content\ContentHandlerFactory->createForModelID()
#3 /store/wikidoc/mediawiki-1.40.0/includes/page/WikiPage.php(311): MediaWiki\Content\ContentHandlerFactory->getContentHandler()
#4 /store/wikidoc/mediawiki-1.40.0/includes/page/WikiPage.php(297): WikiPage->getContentHandler()
#5 /store/wikidoc/mediawiki-1.40.0/includes/page/Article.php(2112): WikiPage->getActionOverrides()
#6 /store/wikidoc/mediawiki-1.40.0/includes/actions/ActionFactory.php(270): Article->getActionOverrides()
#7 /store/wikidoc/mediawiki-1.40.0/includes/actions/ActionFactory.php(373): MediaWiki\Actions\ActionFactory->getAction()
#8 /store/wikidoc/mediawiki-1.40.0/includes/context/RequestContext.php(291): MediaWiki\Actions\ActionFactory->getActionName()
#9 /store/wikidoc/mediawiki-1.40.0/includes/skins/Skin.php(143): RequestContext->getActionName()
#10 /store/wikidoc/mediawiki-1.40.0/includes/skins/SkinTemplate.php(188): Skin->getTemplateData()
#11 /store/wikidoc/mediawiki-1.40.0/includes/skins/SkinMustache.php(92): SkinTemplate->getTemplateData()
#12 /store/wikidoc/mediawiki-1.40.0/skins/Vector/includes/SkinVectorLegacy.php(161): SkinMustache->getTemplateData()
#13 /store/wikidoc/mediawiki-1.40.0/includes/skins/SkinMustache.php(62): MediaWiki\Skins\Vector\SkinVectorLegacy->getTemplateData()
#14 /store/wikidoc/mediawiki-1.40.0/includes/skins/SkinTemplate.php(181): SkinMustache->generateHTML()
#15 /store/wikidoc/mediawiki-1.40.0/includes/OutputPage.php(2899): SkinTemplate->outputPage()
#16 /store/wikidoc/mediawiki-1.40.0/includes/exception/MWException.php(184): OutputPage->output()
#17 /store/wikidoc/mediawiki-1.40.0/includes/exception/MWException.php(218): MWException->reportHTML()
#18 /store/wikidoc/mediawiki-1.40.0/includes/exception/MWExceptionHandler.php(130): MWException->report()
#19 /store/wikidoc/mediawiki-1.40.0/includes/exception/MWExceptionHandler.php(249): MWExceptionHandler::report()
#20 /store/wikidoc/mediawiki-1.40.0/includes/MediaWiki.php(595): MWExceptionHandler::handleException()
#21 /store/wikidoc/mediawiki-1.40.0/index.php(50): MediaWiki->run()
#22 /store/wikidoc/mediawiki-1.40.0/index.php(46): wfIndexMain()
#23 {main}