MediaWiki internal error.

Original exception: [e84ffc9fbe0c38f046760881] /wiki/Item:Q766515 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 = 6062737
Function: MediaWiki\Revision\RevisionStore::loadSlotRecordsFromDb
Error: 2006 MySQL server has gone away

Backtrace:
from /var/www/html/w/includes/libs/rdbms/database/Database.php(1230)
#0 /var/www/html/w/includes/libs/rdbms/database/Database.php(1216): Wikimedia\Rdbms\Database->getQueryException(string, int, string, string)
#1 /var/www/html/w/includes/libs/rdbms/database/Database.php(1190): 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(1367): 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(1449): Wikimedia\Rdbms\SelectQueryBuilder->fetchResultSet()
#8 /var/www/html/w/includes/Revision/RevisionStore.php(1397): MediaWiki\Revision\RevisionStore->loadSlotRecordsFromDb(int, int, MediaWiki\Title\Title)
#9 /var/www/html/w/includes/Revision/RevisionStore.php(1569): MediaWiki\Revision\RevisionStore->loadSlotRecords(int, int, MediaWiki\Title\Title)
#10 /var/www/html/w/includes/Revision/RevisionSlots.php(170): MediaWiki\Revision\RevisionStore->MediaWiki\Revision\{closure}()
#11 /var/www/html/w/includes/Revision/RevisionSlots.php(129): MediaWiki\Revision\RevisionSlots->getSlots()
#12 /var/www/html/w/includes/Revision/RevisionRecord.php(255): MediaWiki\Revision\RevisionSlots->hasSlot(string)
#13 /var/www/html/w/includes/parser/Parser.php(3800): MediaWiki\Revision\RevisionRecord->hasSlot(string)
#14 /var/www/html/w/includes/parser/Parser.php(3668): MediaWiki\Parser\Parser::statelessFetchTemplate(MediaWiki\Title\Title, MediaWiki\Parser\Parser)
#15 /var/www/html/w/extensions/Scribunto/includes/ScribuntoEngineBase.php(177): MediaWiki\Parser\Parser->fetchTemplateAndTitle(MediaWiki\Title\Title)
#16 /var/www/html/w/extensions/Scribunto/includes/Engines/LuaCommon/LuaEngine.php(590): MediaWiki\Extension\Scribunto\ScribuntoEngineBase->fetchModuleFromParser(MediaWiki\Title\Title)
#17 /var/www/html/w/extensions/Scribunto/includes/Engines/LuaStandalone/LuaStandaloneInterpreter.php(402): MediaWiki\Extension\Scribunto\Engines\LuaCommon\LuaEngine->loadPackage(string)
#18 /var/www/html/w/extensions/Scribunto/includes/Engines/LuaStandalone/LuaStandaloneInterpreter.php(373): MediaWiki\Extension\Scribunto\Engines\LuaStandalone\LuaStandaloneInterpreter->callback(string, array)
#19 /var/www/html/w/extensions/Scribunto/includes/Engines/LuaStandalone/LuaStandaloneInterpreter.php(449): MediaWiki\Extension\Scribunto\Engines\LuaStandalone\LuaStandaloneInterpreter->handleCall(array)
#20 /var/www/html/w/extensions/Scribunto/includes/Engines/LuaStandalone/LuaStandaloneInterpreter.php(280): MediaWiki\Extension\Scribunto\Engines\LuaStandalone\LuaStandaloneInterpreter->dispatch(array)
#21 /var/www/html/w/extensions/Scribunto/includes/Engines/LuaCommon/LuaEngine.php(289): MediaWiki\Extension\Scribunto\Engines\LuaStandalone\LuaStandaloneInterpreter->callFunction(MediaWiki\Extension\Scribunto\Engines\LuaStandalone\LuaStandaloneInterpreterFunction, MediaWiki\Extension\Scribunto\Engines\LuaStandalone\LuaStandaloneInterpreterFunction, string)
#22 /var/www/html/w/extensions/Scribunto/includes/Engines/LuaCommon/LuaModule.php(63): MediaWiki\Extension\Scribunto\Engines\LuaCommon\LuaEngine->executeModule(MediaWiki\Extension\Scribunto\Engines\LuaStandalone\LuaStandaloneInterpreterFunction, string, MediaWiki\Parser\PPTemplateFrame_Hash)
#23 /var/www/html/w/extensions/Scribunto/includes/Hooks.php(196): MediaWiki\Extension\Scribunto\Engines\LuaCommon\LuaModule->invoke(string, MediaWiki\Parser\PPTemplateFrame_Hash)
#24 /var/www/html/w/includes/parser/Parser.php(3492): MediaWiki\Extension\Scribunto\Hooks->invokeHook(MediaWiki\Parser\Parser, MediaWiki\Parser\PPTemplateFrame_Hash, array)
#25 /var/www/html/w/includes/parser/Parser.php(3148): MediaWiki\Parser\Parser->callParserFunction(MediaWiki\Parser\PPTemplateFrame_Hash, string, array, bool)
#26 /var/www/html/w/includes/parser/PPFrame_Hash.php(280): MediaWiki\Parser\Parser->braceSubstitution(array, MediaWiki\Parser\PPTemplateFrame_Hash)
#27 /var/www/html/w/includes/parser/Parser.php(3348): MediaWiki\Parser\PPFrame_Hash->expand(MediaWiki\Parser\PPNode_Hash_Tree)
#28 /var/www/html/w/includes/parser/PPFrame_Hash.php(280): MediaWiki\Parser\Parser->braceSubstitution(array, MediaWiki\Parser\PPTemplateFrame_Hash)
#29 /var/www/html/w/includes/parser/Parser.php(3348): MediaWiki\Parser\PPFrame_Hash->expand(MediaWiki\Parser\PPNode_Hash_Tree)
#30 /var/www/html/w/includes/parser/PPFrame_Hash.php(280): MediaWiki\Parser\Parser->braceSubstitution(array, MediaWiki\Parser\PPTemplateFrame_Hash)
#31 /var/www/html/w/includes/parser/Parser.php(3348): MediaWiki\Parser\PPFrame_Hash->expand(MediaWiki\Parser\PPNode_Hash_Tree)
#32 /var/www/html/w/includes/parser/PPFrame_Hash.php(280): MediaWiki\Parser\Parser->braceSubstitution(array, MediaWiki\Parser\PPFrame_Hash)
#33 /var/www/html/w/includes/parser/Parser.php(2970): MediaWiki\Parser\PPFrame_Hash->expand(MediaWiki\Parser\PPNode_Hash_Tree, int)
#34 /var/www/html/w/includes/parser/Parser.php(1606): MediaWiki\Parser\Parser->replaceVariables(string)
#35 /var/www/html/w/includes/parser/Parser.php(705): MediaWiki\Parser\Parser->internalParse(string)
#36 /var/www/html/w/includes/Output/OutputPage.php(2750): MediaWiki\Parser\Parser->parse(string, MediaWiki\Title\Title, MediaWiki\Parser\ParserOptions, bool, bool, null)
#37 /var/www/html/w/includes/Output/OutputPage.php(2271): MediaWiki\Output\OutputPage->parseInternal(string, MediaWiki\Title\Title, bool, bool, bool, null, bool)
#38 /var/www/html/w/includes/Output/OutputPage.php(2250): MediaWiki\Output\OutputPage->addWikiTextTitleInternal(string, MediaWiki\Title\Title, bool, bool)
#39 /shared/LocalSettings.d/mardi02_hooks.php(18): MediaWiki\Output\OutputPage->addWikiTextAsContent(string)
#40 /var/www/html/w/includes/HookContainer/HookContainer.php(155): {closure}(MediaWiki\Page\Article, null, bool)
#41 /var/www/html/w/includes/HookContainer/HookRunner.php(878): MediaWiki\HookContainer\HookContainer->run(string, array)
#42 /var/www/html/w/includes/page/Article.php(709): MediaWiki\HookContainer\HookRunner->onArticleViewHeader(MediaWiki\Page\Article, null, bool)
#43 /var/www/html/w/includes/page/Article.php(552): MediaWiki\Page\Article->generateContentOutput(MediaWiki\User\User, MediaWiki\Parser\ParserOptions, int, MediaWiki\Output\OutputPage, array)
#44 /var/www/html/w/extensions/Wikibase/repo/includes/Actions/ViewEntityAction.php(80): MediaWiki\Page\Article->view()
#45 /var/www/html/w/extensions/Wikibase/repo/includes/Actions/ViewEntityAction.php(55): Wikibase\Repo\Actions\ViewEntityAction->showEntityPage()
#46 /var/www/html/w/includes/actions/ActionEntryPoint.php(728): Wikibase\Repo\Actions\ViewEntityAction->show()
#47 /var/www/html/w/includes/actions/ActionEntryPoint.php(505): MediaWiki\Actions\ActionEntryPoint->performAction(MediaWiki\Page\Article, MediaWiki\Title\Title)
#48 /var/www/html/w/includes/actions/ActionEntryPoint.php(143): MediaWiki\Actions\ActionEntryPoint->performRequest()
#49 /var/www/html/w/includes/MediaWikiEntryPoint.php(202): MediaWiki\Actions\ActionEntryPoint->execute()
#50 /var/www/html/w/index.php(58): MediaWiki\MediaWikiEntryPoint->run()
#51 {main}

Exception caught inside exception handler: [e84ffc9fbe0c38f046760881] /wiki/Item:Q766515 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(994): MediaWiki\HookContainer\HookContainer->run(string, array, array)
#12 /var/www/html/w/includes/Output/OutputPage.php(3278): MediaWiki\HookContainer\HookRunner->onBeforePageDisplay(MediaWiki\Output\OutputPage, Skins\Chameleon\Chameleon)
#13 /var/www/html/w/includes/exception/MWExceptionRenderer.php(196): MediaWiki\Output\OutputPage->output()
#14 /var/www/html/w/includes/exception/MWExceptionRenderer.php(116): MediaWiki\Exception\MWExceptionRenderer::reportHTML(Wikimedia\Rdbms\DBQueryDisconnectedError)
#15 /var/www/html/w/includes/exception/MWExceptionHandler.php(137): MediaWiki\Exception\MWExceptionRenderer::output(Wikimedia\Rdbms\DBQueryDisconnectedError, int)
#16 /var/www/html/w/includes/exception/MWExceptionHandler.php(241): MediaWiki\Exception\MWExceptionHandler::report(Wikimedia\Rdbms\DBQueryDisconnectedError)
#17 /var/www/html/w/includes/MediaWikiEntryPoint.php(222): MediaWiki\Exception\MWExceptionHandler::handleException(Wikimedia\Rdbms\DBQueryDisconnectedError, string)
#18 /var/www/html/w/includes/actions/ActionEntryPoint.php(79): 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}