MediaWiki internal error.

Original exception: [f86f70c694147e9055af6058] /index.php?title=User_talk:3.236.51.151&action=new-topic 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 /home/onewqdcw/public_html/includes/content/ContentHandlerFactory.php(203)
#0 /home/onewqdcw/public_html/includes/content/ContentHandlerFactory.php(272): MediaWiki\Content\ContentHandlerFactory->validateContentHandler(string, NULL)
#1 /home/onewqdcw/public_html/includes/content/ContentHandlerFactory.php(191): MediaWiki\Content\ContentHandlerFactory->createContentHandlerFromHook(string)
#2 /home/onewqdcw/public_html/includes/content/ContentHandlerFactory.php(97): MediaWiki\Content\ContentHandlerFactory->createForModelID(string)
#3 /home/onewqdcw/public_html/includes/MediaWiki.php(435): MediaWiki\Content\ContentHandlerFactory->getContentHandler(string)
#4 /home/onewqdcw/public_html/includes/MediaWiki.php(318): MediaWiki->initializeArticle()
#5 /home/onewqdcw/public_html/includes/MediaWiki.php(925): MediaWiki->performRequest()
#6 /home/onewqdcw/public_html/includes/MediaWiki.php(559): MediaWiki->main()
#7 /home/onewqdcw/public_html/index.php(53): MediaWiki->run()
#8 /home/onewqdcw/public_html/index.php(46): wfIndexMain()
#9 {main}

Exception caught inside exception handler: [f86f70c694147e9055af6058] /index.php?title=User_talk:3.236.51.151&action=new-topic 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 /home/onewqdcw/public_html/includes/content/ContentHandlerFactory.php(203)
#0 /home/onewqdcw/public_html/includes/content/ContentHandlerFactory.php(272): MediaWiki\Content\ContentHandlerFactory->validateContentHandler(string, NULL)
#1 /home/onewqdcw/public_html/includes/content/ContentHandlerFactory.php(191): MediaWiki\Content\ContentHandlerFactory->createContentHandlerFromHook(string)
#2 /home/onewqdcw/public_html/includes/content/ContentHandlerFactory.php(97): MediaWiki\Content\ContentHandlerFactory->createForModelID(string)
#3 /home/onewqdcw/public_html/includes/Title.php(4018): MediaWiki\Content\ContentHandlerFactory->getContentHandler(string)
#4 /home/onewqdcw/public_html/includes/skins/SkinTemplate.php(1482): Title->getPageLanguage()
#5 /home/onewqdcw/public_html/includes/skins/SkinTemplate.php(414): SkinTemplate->buildContentNavigationUrls()
#6 /home/onewqdcw/public_html/includes/skins/SkinTemplate.php(127): SkinTemplate->prepareQuickTemplate()
#7 /home/onewqdcw/public_html/includes/skins/SkinTemplate.php(144): SkinTemplate->generateHTML()
#8 /home/onewqdcw/public_html/includes/OutputPage.php(2644): SkinTemplate->outputPage()
#9 /home/onewqdcw/public_html/includes/exception/MWException.php(193): OutputPage->output()
#10 /home/onewqdcw/public_html/includes/exception/MWException.php(231): MWException->reportHTML()
#11 /home/onewqdcw/public_html/includes/exception/MWExceptionHandler.php(105): MWException->report()
#12 /home/onewqdcw/public_html/includes/exception/MWExceptionHandler.php(202): MWExceptionHandler::report(MWUnknownContentModelException)
#13 /home/onewqdcw/public_html/includes/MediaWiki.php(578): MWExceptionHandler::handleException(MWUnknownContentModelException, string)
#14 /home/onewqdcw/public_html/index.php(53): MediaWiki->run()
#15 /home/onewqdcw/public_html/index.php(46): wfIndexMain()
#16 {main}