MediaWiki internal error.

Original exception: [1018f30ee7b932a3010e8a0c] /wiki/Biology:Urocoras Wikimedia\Rdbms\DBQueryDisconnectedError: A database query error has occurred. Did you forget to run your application's database schema updater after upgrading or after adding a new extension?

Please see https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:Upgrading and https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:How_to_debug for more information.

A connection error occurred during a query.
Query: SELECT page_id,page_namespace,page_title,page_is_redirect,page_is_new,page_touched,page_links_updated,page_latest,page_len,page_content_model,page_restrictions FROM `page` WHERE page_namespace = 10 AND page_title = 'MONTHNAME' LIMIT 1
Function: MediaWiki\Page\PageStore::getPageByNameViaLinkCache
Error: 2006 MySQL server has gone away (localhost)

Backtrace:
from /var/www/html/handwiki/public_html/wiki/includes/libs/rdbms/database/Database.php(1604)
#0 /var/www/html/handwiki/public_html/wiki/includes/libs/rdbms/database/Database.php(1590): Wikimedia\Rdbms\Database->getQueryException()
#1 /var/www/html/handwiki/public_html/wiki/includes/libs/rdbms/database/Database.php(1564): Wikimedia\Rdbms\Database->getQueryExceptionAndLog()
#2 /var/www/html/handwiki/public_html/wiki/includes/libs/rdbms/database/Database.php(1173): Wikimedia\Rdbms\Database->reportQueryError()
#3 /var/www/html/handwiki/public_html/wiki/includes/libs/rdbms/database/Database.php(1810): Wikimedia\Rdbms\Database->query()
#4 /var/www/html/handwiki/public_html/wiki/includes/libs/rdbms/database/Database.php(1911): Wikimedia\Rdbms\Database->select()
#5 /var/www/html/handwiki/public_html/wiki/includes/libs/rdbms/database/DBConnRef.php(69): Wikimedia\Rdbms\Database->selectRow()
#6 /var/www/html/handwiki/public_html/wiki/includes/libs/rdbms/database/DBConnRef.php(337): Wikimedia\Rdbms\DBConnRef->__call()
#7 /var/www/html/handwiki/public_html/wiki/includes/libs/rdbms/querybuilder/SelectQueryBuilder.php(686): Wikimedia\Rdbms\DBConnRef->selectRow()
#8 /var/www/html/handwiki/public_html/wiki/includes/page/PageStore.php(199): Wikimedia\Rdbms\SelectQueryBuilder->fetchRow()
#9 /var/www/html/handwiki/public_html/wiki/includes/cache/LinkCache.php(480): MediaWiki\Page\PageStore->MediaWiki\Page\{closure}()
#10 /var/www/html/handwiki/public_html/wiki/includes/libs/objectcache/wancache/WANObjectCache.php(1685): LinkCache->{closure}()
#11 /var/www/html/handwiki/public_html/wiki/includes/libs/objectcache/wancache/WANObjectCache.php(1518): WANObjectCache->fetchOrRegenerate()
#12 /var/www/html/handwiki/public_html/wiki/includes/cache/LinkCache.php(485): WANObjectCache->getWithSetCallback()
#13 /var/www/html/handwiki/public_html/wiki/includes/cache/LinkCache.php(524): LinkCache->getGoodLinkRowInternal()
#14 /var/www/html/handwiki/public_html/wiki/includes/page/PageStore.php(188): LinkCache->getGoodLinkRow()
#15 /var/www/html/handwiki/public_html/wiki/includes/page/PageStore.php(154): MediaWiki\Page\PageStore->getPageByNameViaLinkCache()
#16 /var/www/html/handwiki/public_html/wiki/includes/page/PageStore.php(326): MediaWiki\Page\PageStore->getPageByName()
#17 /var/www/html/handwiki/public_html/wiki/includes/Title.php(4121): MediaWiki\Page\PageStore->getPageByReference()
#18 /var/www/html/handwiki/public_html/wiki/includes/Title.php(2872): Title->getFieldFromPageStore()
#19 /var/www/html/handwiki/public_html/wiki/includes/page/LegacyArticleIdAccess.php(43): Title->getArticleID()
#20 /var/www/html/handwiki/public_html/wiki/includes/Revision/RevisionStore.php(2923): MediaWiki\Revision\RevisionStore->getArticleId()
#21 /var/www/html/handwiki/public_html/wiki/includes/parser/Parser.php(3563): MediaWiki\Revision\RevisionStore->getKnownCurrentRevision()
#22 [internal function]: Parser::statelessFetchRevisionRecord()
#23 /var/www/html/handwiki/public_html/wiki/includes/Revision/RenderedRevision.php(397): call_user_func()
#24 /var/www/html/handwiki/public_html/wiki/includes/parser/Parser.php(3516): MediaWiki\Revision\RenderedRevision->MediaWiki\Revision\{closure}()
#25 /var/www/html/handwiki/public_html/wiki/includes/parser/Parser.php(3667): Parser->fetchCurrentRevisionRecordOfTitle()
#26 /var/www/html/handwiki/public_html/wiki/includes/parser/Parser.php(3579): Parser::statelessFetchTemplate()
#27 /var/www/html/handwiki/public_html/wiki/includes/parser/Parser.php(3473): Parser->fetchTemplateAndTitle()
#28 /var/www/html/handwiki/public_html/wiki/includes/parser/Parser.php(3212): Parser->getTemplateDom()
#29 /var/www/html/handwiki/public_html/wiki/includes/parser/PPFrame_Hash.php(276): Parser->braceSubstitution()
#30 /var/www/html/handwiki/public_html/wiki/extensions/ParserFunctions/includes/ParserFunctions.php(121): PPFrame_Hash->expand()
#31 /var/www/html/handwiki/public_html/wiki/includes/parser/Parser.php(3413): MediaWiki\Extension\ParserFunctions\ParserFunctions::if()
#32 /var/www/html/handwiki/public_html/wiki/includes/parser/Parser.php(3096): Parser->callParserFunction()
#33 /var/www/html/handwiki/public_html/wiki/includes/parser/PPFrame_Hash.php(276): Parser->braceSubstitution()
#34 /var/www/html/handwiki/public_html/wiki/includes/parser/Parser.php(3287): PPFrame_Hash->expand()
#35 /var/www/html/handwiki/public_html/wiki/includes/parser/PPFrame_Hash.php(276): Parser->braceSubstitution()
#36 /var/www/html/handwiki/public_html/wiki/includes/parser/Parser.php(2932): PPFrame_Hash->expand()
#37 /var/www/html/handwiki/public_html/wiki/includes/parser/Parser.php(1579): Parser->replaceVariables()
#38 /var/www/html/handwiki/public_html/wiki/includes/parser/Parser.php(697): Parser->internalParse()
#39 /var/www/html/handwiki/public_html/wiki/includes/content/WikitextContentHandler.php(294): Parser->parse()
#40 /var/www/html/handwiki/public_html/wiki/includes/content/ContentHandler.php(1705): WikitextContentHandler->fillParserOutput()
#41 /var/www/html/handwiki/public_html/wiki/includes/content/Renderer/ContentRenderer.php(47): ContentHandler->getParserOutput()
#42 /var/www/html/handwiki/public_html/wiki/includes/Revision/RenderedRevision.php(267): MediaWiki\Content\Renderer\ContentRenderer->getParserOutput()
#43 /var/www/html/handwiki/public_html/wiki/includes/Revision/RenderedRevision.php(238): MediaWiki\Revision\RenderedRevision->getSlotParserOutputUncached()
#44 /var/www/html/handwiki/public_html/wiki/includes/Revision/RevisionRenderer.php(221): MediaWiki\Revision\RenderedRevision->getSlotParserOutput()
#45 /var/www/html/handwiki/public_html/wiki/includes/Revision/RevisionRenderer.php(158): MediaWiki\Revision\RevisionRenderer->combineSlotOutput()
#46 [internal function]: MediaWiki\Revision\RevisionRenderer->MediaWiki\Revision\{closure}()
#47 /var/www/html/handwiki/public_html/wiki/includes/Revision/RenderedRevision.php(200): call_user_func()
#48 /var/www/html/handwiki/public_html/wiki/includes/poolcounter/PoolWorkArticleView.php(137): MediaWiki\Revision\RenderedRevision->getRevisionParserOutput()
#49 /var/www/html/handwiki/public_html/wiki/includes/poolcounter/PoolCounterWork.php(162): PoolWorkArticleView->doWork()
#50 /var/www/html/handwiki/public_html/wiki/includes/page/ParserOutputAccess.php(302): PoolCounterWork->execute()
#51 /var/www/html/handwiki/public_html/wiki/includes/page/Article.php(702): MediaWiki\Page\ParserOutputAccess->getParserOutput()
#52 /var/www/html/handwiki/public_html/wiki/includes/page/Article.php(517): Article->generateContentOutput()
#53 /var/www/html/handwiki/public_html/wiki/includes/actions/ViewAction.php(80): Article->view()
#54 /var/www/html/handwiki/public_html/wiki/includes/MediaWiki.php(543): ViewAction->show()
#55 /var/www/html/handwiki/public_html/wiki/includes/MediaWiki.php(321): MediaWiki->performAction()
#56 /var/www/html/handwiki/public_html/wiki/includes/MediaWiki.php(912): MediaWiki->performRequest()
#57 /var/www/html/handwiki/public_html/wiki/includes/MediaWiki.php(563): MediaWiki->main()
#58 /var/www/html/handwiki/public_html/wiki/index.php(53): MediaWiki->run()
#59 /var/www/html/handwiki/public_html/wiki/index.php(46): wfIndexMain()
#60 {main}

Exception caught inside exception handler: [1018f30ee7b932a3010e8a0c] /wiki/Biology:Urocoras Wikimedia\Rdbms\DBConnectionError: Cannot access the database: No such file or directory (localhost) (localhost)
Backtrace:
from /var/www/html/handwiki/public_html/wiki/includes/libs/rdbms/loadbalancer/LoadBalancer.php(1460)
#0 /var/www/html/handwiki/public_html/wiki/includes/libs/rdbms/loadbalancer/LoadBalancer.php(977): Wikimedia\Rdbms\LoadBalancer->reportConnectionError()
#1 /var/www/html/handwiki/public_html/wiki/includes/libs/rdbms/loadbalancer/LoadBalancer.php(928): Wikimedia\Rdbms\LoadBalancer->getServerConnection()
#2 /var/www/html/handwiki/public_html/wiki/includes/libs/rdbms/loadbalancer/LoadBalancer.php(1086): Wikimedia\Rdbms\LoadBalancer->getConnection()
#3 /var/www/html/handwiki/public_html/wiki/includes/GlobalFunctions.php(2208): Wikimedia\Rdbms\LoadBalancer->getMaintenanceConnectionRef()
#4 /var/www/html/handwiki/public_html/wiki/extensions/PageImages/includes/PageImages.php(103): wfGetDB()
#5 /var/www/html/handwiki/public_html/wiki/extensions/PageImages/includes/PageImages.php(253): PageImages\PageImages::getPageImage()
#6 /var/www/html/handwiki/public_html/wiki/includes/HookContainer/HookContainer.php(338): PageImages\PageImages::onBeforePageDisplay()
#7 /var/www/html/handwiki/public_html/wiki/includes/HookContainer/HookContainer.php(137): MediaWiki\HookContainer\HookContainer->callLegacyHook()
#8 /var/www/html/handwiki/public_html/wiki/includes/HookContainer/HookRunner.php(939): MediaWiki\HookContainer\HookContainer->run()
#9 /var/www/html/handwiki/public_html/wiki/includes/OutputPage.php(2802): MediaWiki\HookContainer\HookRunner->onBeforePageDisplay()
#10 /var/www/html/handwiki/public_html/wiki/includes/exception/MWExceptionRenderer.php(157): OutputPage->output()
#11 /var/www/html/handwiki/public_html/wiki/includes/exception/MWExceptionRenderer.php(76): MWExceptionRenderer::reportHTML()
#12 /var/www/html/handwiki/public_html/wiki/includes/exception/MWExceptionHandler.php(107): MWExceptionRenderer::output()
#13 /var/www/html/handwiki/public_html/wiki/includes/exception/MWExceptionHandler.php(202): MWExceptionHandler::report()
#14 /var/www/html/handwiki/public_html/wiki/includes/MediaWiki.php(582): MWExceptionHandler::handleException()
#15 /var/www/html/handwiki/public_html/wiki/index.php(53): MediaWiki->run()
#16 /var/www/html/handwiki/public_html/wiki/index.php(46): wfIndexMain()
#17 {main}