MediaWiki internal error.

Original exception: [16702042d3d9ff5e3a62d73b] /wiki/Publication:1801201 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 slot_revision_id,slot_content_id,slot_origin,slot_role_id,content_size,content_sha1,content_address,content_model FROM `slots` JOIN `content` ON ((slot_content_id = content_id)) WHERE slot_revision_id = 23136955
Function: MediaWiki\Revision\RevisionStore::loadSlotRecordsFromDb
Error: 2006 MySQL server has gone away

Backtrace:
from /var/www/html/w/includes/libs/rdbms/database/Database.php(1228)
#0 /var/www/html/w/includes/libs/rdbms/database/Database.php(1214): Wikimedia\Rdbms\Database->getQueryException(string, int, string, string)
#1 /var/www/html/w/includes/libs/rdbms/database/Database.php(1188): Wikimedia\Rdbms\Database->getQueryExceptionAndLog(string, int, string, string)
#2 /var/www/html/w/includes/libs/rdbms/database/Database.php(647): Wikimedia\Rdbms\Database->reportQueryError(string, int, string, string, bool)
#3 /var/www/html/w/includes/libs/rdbms/database/Database.php(1365): Wikimedia\Rdbms\Database->query(Wikimedia\Rdbms\Query, string)
#4 /var/www/html/w/includes/libs/rdbms/database/DBConnRef.php(127): Wikimedia\Rdbms\Database->select(array, array, array, string, array, array)
#5 /var/www/html/w/includes/libs/rdbms/database/DBConnRef.php(351): Wikimedia\Rdbms\DBConnRef->__call(string, array)
#6 /var/www/html/w/includes/libs/rdbms/querybuilder/SelectQueryBuilder.php(762): Wikimedia\Rdbms\DBConnRef->select(array, array, array, string, array, array)
#7 /var/www/html/w/includes/Revision/RevisionStore.php(1451): Wikimedia\Rdbms\SelectQueryBuilder->fetchResultSet()
#8 /var/www/html/w/includes/Revision/RevisionStore.php(1399): MediaWiki\Revision\RevisionStore->loadSlotRecordsFromDb(int, int, MediaWiki\Title\Title)
#9 /var/www/html/w/includes/Revision/RevisionStore.php(1571): MediaWiki\Revision\RevisionStore->loadSlotRecords(int, int, MediaWiki\Title\Title)
#10 [internal function]: MediaWiki\Revision\RevisionStore->MediaWiki\Revision\{closure}()
#11 /var/www/html/w/includes/Revision/RevisionSlots.php(170): call_user_func(Closure)
#12 /var/www/html/w/includes/Revision/RevisionSlots.php(129): MediaWiki\Revision\RevisionSlots->getSlots()
#13 /var/www/html/w/includes/Revision/RevisionRecord.php(255): MediaWiki\Revision\RevisionSlots->hasSlot(string)
#14 /var/www/html/w/includes/parser/Parser.php(3803): MediaWiki\Revision\RevisionRecord->hasSlot(string)
#15 /var/www/html/w/includes/parser/Parser.php(3669): MediaWiki\Parser\Parser::statelessFetchTemplate(MediaWiki\Title\Title, MediaWiki\Parser\Parser)
#16 /var/www/html/w/extensions/Scribunto/includes/ScribuntoEngineBase.php(177): MediaWiki\Parser\Parser->fetchTemplateAndTitle(MediaWiki\Title\Title)
#17 /var/www/html/w/extensions/Scribunto/includes/Hooks.php(166): MediaWiki\Extension\Scribunto\ScribuntoEngineBase->fetchModuleFromParser(MediaWiki\Title\Title)
#18 /var/www/html/w/includes/parser/Parser.php(3487): MediaWiki\Extension\Scribunto\Hooks->invokeHook(MediaWiki\Parser\Parser, MediaWiki\Parser\PPTemplateFrame_Hash, array)
#19 /var/www/html/w/includes/parser/Parser.php(3143): MediaWiki\Parser\Parser->callParserFunction(MediaWiki\Parser\PPTemplateFrame_Hash, string, array, bool)
#20 /var/www/html/w/includes/parser/PPFrame_Hash.php(280): MediaWiki\Parser\Parser->braceSubstitution(array, MediaWiki\Parser\PPTemplateFrame_Hash)
#21 /var/www/html/w/includes/parser/PPTemplateFrame_Hash.php(100): MediaWiki\Parser\PPFrame_Hash->expand(MediaWiki\Parser\PPNode_Hash_Tree, int)
#22 /var/www/html/w/includes/parser/Parser.php(3340): MediaWiki\Parser\PPTemplateFrame_Hash->cachedExpand(string, MediaWiki\Parser\PPNode_Hash_Tree)
#23 /var/www/html/w/includes/parser/PPFrame_Hash.php(280): MediaWiki\Parser\Parser->braceSubstitution(array, MediaWiki\Parser\PPFrame_Hash)
#24 /var/www/html/w/includes/parser/Parser.php(2969): MediaWiki\Parser\PPFrame_Hash->expand(MediaWiki\Parser\PPNode_Hash_Tree, int)
#25 /var/www/html/w/includes/parser/Parser.php(1601): MediaWiki\Parser\Parser->replaceVariables(string)
#26 /var/www/html/w/includes/parser/Parser.php(700): MediaWiki\Parser\Parser->internalParse(string)
#27 /var/www/html/w/includes/content/WikitextContentHandler.php(384): MediaWiki\Parser\Parser->parse(string, MediaWiki\Title\Title, MediaWiki\Parser\ParserOptions, bool, bool, int)
#28 /var/www/html/w/includes/content/ContentHandler.php(1697): MediaWiki\Content\WikitextContentHandler->fillParserOutput(MediaWiki\Content\WikitextContent, MediaWiki\Content\Renderer\ContentParseParams, MediaWiki\Parser\ParserOutput)
#29 /var/www/html/w/includes/content/Renderer/ContentRenderer.php(75): MediaWiki\Content\ContentHandler->getParserOutput(MediaWiki\Content\WikitextContent, MediaWiki\Content\Renderer\ContentParseParams)
#30 /var/www/html/w/includes/Revision/RenderedRevision.php(261): MediaWiki\Content\Renderer\ContentRenderer->getParserOutput(MediaWiki\Content\WikitextContent, MediaWiki\Page\PageIdentityValue, MediaWiki\Revision\RevisionStoreRecord, MediaWiki\Parser\ParserOptions, array)
#31 /var/www/html/w/includes/Revision/RenderedRevision.php(233): MediaWiki\Revision\RenderedRevision->getSlotParserOutputUncached(MediaWiki\Content\WikitextContent, array)
#32 /var/www/html/w/includes/Revision/RevisionRenderer.php(236): MediaWiki\Revision\RenderedRevision->getSlotParserOutput(string, array)
#33 /var/www/html/w/includes/Revision/RevisionRenderer.php(169): MediaWiki\Revision\RevisionRenderer->combineSlotOutput(MediaWiki\Revision\RenderedRevision, MediaWiki\Parser\ParserOptions, array)
#34 [internal function]: MediaWiki\Revision\RevisionRenderer->MediaWiki\Revision\{closure}(MediaWiki\Revision\RenderedRevision, array)
#35 /var/www/html/w/includes/Revision/RenderedRevision.php(196): call_user_func(Closure, MediaWiki\Revision\RenderedRevision, array)
#36 /var/www/html/w/includes/poolcounter/PoolWorkArticleView.php(106): MediaWiki\Revision\RenderedRevision->getRevisionParserOutput()
#37 /var/www/html/w/includes/poolcounter/PoolWorkArticleViewCurrent.php(123): MediaWiki\PoolCounter\PoolWorkArticleView->renderRevision(null, bool, string)
#38 /var/www/html/w/includes/poolcounter/PoolCounterWork.php(171): MediaWiki\PoolCounter\PoolWorkArticleViewCurrent->doWork()
#39 /var/www/html/w/includes/page/ParserOutputAccess.php(369): MediaWiki\PoolCounter\PoolCounterWork->execute()
#40 /var/www/html/w/includes/page/Article.php(829): MediaWiki\Page\ParserOutputAccess->getParserOutput(WikiPage, MediaWiki\Parser\ParserOptions, MediaWiki\Revision\RevisionStoreRecord, int)
#41 /var/www/html/w/includes/page/Article.php(545): Article->generateContentOutput(MediaWiki\User\User, MediaWiki\Parser\ParserOptions, int, MediaWiki\Output\OutputPage, array)
#42 /var/www/html/w/includes/actions/ViewAction.php(78): Article->view()
#43 /var/www/html/w/includes/actions/ActionEntryPoint.php(732): ViewAction->show()
#44 /var/www/html/w/includes/actions/ActionEntryPoint.php(509): MediaWiki\Actions\ActionEntryPoint->performAction(Article, MediaWiki\Title\Title)
#45 /var/www/html/w/includes/actions/ActionEntryPoint.php(145): MediaWiki\Actions\ActionEntryPoint->performRequest()
#46 /var/www/html/w/includes/MediaWikiEntryPoint.php(202): MediaWiki\Actions\ActionEntryPoint->execute()
#47 /var/www/html/w/index.php(58): MediaWiki\MediaWikiEntryPoint->run()
#48 {main}

Exception caught inside exception handler: [16702042d3d9ff5e3a62d73b] /wiki/Publication:1801201 Wikimedia\Rdbms\DBConnectionError: Cannot access the database: Connection refused (mysql.svc:3306)
Backtrace:
from /var/www/html/w/includes/libs/rdbms/loadbalancer/LoadBalancer.php(1131)
#0 /var/www/html/w/includes/libs/rdbms/loadbalancer/LoadBalancer.php(821): Wikimedia\Rdbms\LoadBalancer->reportConnectionError()
#1 /var/www/html/w/includes/libs/rdbms/loadbalancer/LoadBalancer.php(788): Wikimedia\Rdbms\LoadBalancer->getServerConnection(int, string, int)
#2 /var/www/html/w/includes/libs/rdbms/database/DBConnRef.php(111): Wikimedia\Rdbms\LoadBalancer->getConnectionInternal(int, array, string, int)
#3 /var/www/html/w/includes/libs/rdbms/database/DBConnRef.php(125): Wikimedia\Rdbms\DBConnRef->ensureConnection()
#4 /var/www/html/w/includes/libs/rdbms/database/DBConnRef.php(351): Wikimedia\Rdbms\DBConnRef->__call(string, array)
#5 /var/www/html/w/includes/libs/rdbms/querybuilder/SelectQueryBuilder.php(762): Wikimedia\Rdbms\DBConnRef->select(array, array, array, string, array, array)
#6 /var/www/html/w/includes/page/PageProps.php(118): Wikimedia\Rdbms\SelectQueryBuilder->fetchResultSet()
#7 /var/www/html/w/extensions/DisplayTitle/includes/DisplayTitleService.php(204): MediaWiki\Page\PageProps->getProperties(MediaWiki\Title\Title, array)
#8 /var/www/html/w/extensions/DisplayTitle/includes/DisplayTitleService.php(239): MediaWiki\Extension\DisplayTitle\DisplayTitleService->getDisplayTitle(MediaWiki\Title\Title, null)
#9 /var/www/html/w/extensions/DisplayTitle/includes/DisplayTitleHooks.php(169): MediaWiki\Extension\DisplayTitle\DisplayTitleService->setSubtitle(MediaWiki\Output\OutputPage)
#10 /var/www/html/w/includes/HookContainer/HookContainer.php(155): MediaWiki\Extension\DisplayTitle\DisplayTitleHooks->onBeforePageDisplay(MediaWiki\Output\OutputPage, Skins\Chameleon\Chameleon)
#11 /var/www/html/w/includes/HookContainer/HookRunner.php(992): MediaWiki\HookContainer\HookContainer->run(string, array, array)
#12 /var/www/html/w/includes/Output/OutputPage.php(3187): MediaWiki\HookContainer\HookRunner->onBeforePageDisplay(MediaWiki\Output\OutputPage, Skins\Chameleon\Chameleon)
#13 /var/www/html/w/includes/exception/MWExceptionRenderer.php(189): MediaWiki\Output\OutputPage->output()
#14 /var/www/html/w/includes/exception/MWExceptionRenderer.php(110): MWExceptionRenderer::reportHTML(Wikimedia\Rdbms\DBQueryDisconnectedError)
#15 /var/www/html/w/includes/exception/MWExceptionHandler.php(134): MWExceptionRenderer::output(Wikimedia\Rdbms\DBQueryDisconnectedError, int)
#16 /var/www/html/w/includes/exception/MWExceptionHandler.php(238): MWExceptionHandler::report(Wikimedia\Rdbms\DBQueryDisconnectedError)
#17 /var/www/html/w/includes/MediaWikiEntryPoint.php(222): MWExceptionHandler::handleException(Wikimedia\Rdbms\DBQueryDisconnectedError, string)
#18 /var/www/html/w/includes/actions/ActionEntryPoint.php(81): MediaWiki\MediaWikiEntryPoint->handleTopLevelError(Wikimedia\Rdbms\DBQueryDisconnectedError)
#19 /var/www/html/w/includes/MediaWikiEntryPoint.php(208): MediaWiki\Actions\ActionEntryPoint->handleTopLevelError(Wikimedia\Rdbms\DBQueryDisconnectedError)
#20 /var/www/html/w/index.php(58): MediaWiki\MediaWikiEntryPoint->run()
#21 {main}