MediaWiki internal error.

Original exception: [6e52b4bb93d51f54cfa1675d] /wiki/%D9%82%D8%A7%D9%84%D8%A8:In_string/doc 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 pp_value FROM `page_props` WHERE pp_page = 5555 AND pp_propname IN ('page_image','page_image_free') ORDER BY pp_propname LIMIT 1
Function: PageImages\PageImages::fetchPageImage
Error: 2006 MySQL server has gone away

Backtrace:
from /var/www/ar.wikivahdat.com/w/includes/libs/rdbms/database/Database.php(1196)
#0 /var/www/ar.wikivahdat.com/w/includes/libs/rdbms/database/Database.php(1182): Wikimedia\Rdbms\Database->getQueryException()
#1 /var/www/ar.wikivahdat.com/w/includes/libs/rdbms/database/Database.php(1156): Wikimedia\Rdbms\Database->getQueryExceptionAndLog()
#2 /var/www/ar.wikivahdat.com/w/includes/libs/rdbms/database/Database.php(647): Wikimedia\Rdbms\Database->reportQueryError()
#3 /var/www/ar.wikivahdat.com/w/includes/libs/rdbms/database/Database.php(1345): Wikimedia\Rdbms\Database->query()
#4 /var/www/ar.wikivahdat.com/w/includes/libs/rdbms/database/Database.php(1296): Wikimedia\Rdbms\Database->select()
#5 /var/www/ar.wikivahdat.com/w/includes/libs/rdbms/database/DBConnRef.php(127): Wikimedia\Rdbms\Database->selectField()
#6 /var/www/ar.wikivahdat.com/w/includes/libs/rdbms/database/DBConnRef.php(338): Wikimedia\Rdbms\DBConnRef->__call()
#7 /var/www/ar.wikivahdat.com/w/includes/libs/rdbms/querybuilder/SelectQueryBuilder.php(762): Wikimedia\Rdbms\DBConnRef->selectField()
#8 /var/www/ar.wikivahdat.com/w/extensions/PageImages/includes/PageImages.php(201): Wikimedia\Rdbms\SelectQueryBuilder->fetchField()
#9 /var/www/ar.wikivahdat.com/w/extensions/PageImages/includes/PageImages.php(163): PageImages\PageImages->fetchPageImage()
#10 /var/www/ar.wikivahdat.com/w/includes/libs/MapCacheLRU.php(271): PageImages\PageImages->PageImages\{closure}()
#11 /var/www/ar.wikivahdat.com/w/extensions/PageImages/includes/PageImages.php(161): MapCacheLRU->getWithSetCallback()
#12 /var/www/ar.wikivahdat.com/w/extensions/PageImages/includes/PageImages.php(308): PageImages\PageImages->getPageImageInternal()
#13 /var/www/ar.wikivahdat.com/w/includes/HookContainer/HookContainer.php(159): PageImages\PageImages->onBeforePageDisplay()
#14 /var/www/ar.wikivahdat.com/w/includes/HookContainer/HookRunner.php(982): MediaWiki\HookContainer\HookContainer->run()
#15 /var/www/ar.wikivahdat.com/w/includes/Output/OutputPage.php(3186): MediaWiki\HookContainer\HookRunner->onBeforePageDisplay()
#16 /var/www/ar.wikivahdat.com/w/includes/actions/ActionEntryPoint.php(163): MediaWiki\Output\OutputPage->output()
#17 /var/www/ar.wikivahdat.com/w/includes/MediaWikiEntryPoint.php(200): MediaWiki\Actions\ActionEntryPoint->execute()
#18 /var/www/ar.wikivahdat.com/w/index.php(58): MediaWiki\MediaWikiEntryPoint->run()
#19 {main}

Exception caught inside exception handler: [6e52b4bb93d51f54cfa1675d] /wiki/%D9%82%D8%A7%D9%84%D8%A8:In_string/doc Wikimedia\Rdbms\DBConnectionError: Cannot access the database: MySQL server has gone away (localhost)
Backtrace:
from /var/www/ar.wikivahdat.com/w/includes/libs/rdbms/loadbalancer/LoadBalancer.php(1129)
#0 /var/www/ar.wikivahdat.com/w/includes/libs/rdbms/loadbalancer/LoadBalancer.php(817): Wikimedia\Rdbms\LoadBalancer->reportConnectionError()
#1 /var/www/ar.wikivahdat.com/w/includes/libs/rdbms/loadbalancer/LoadBalancer.php(784): Wikimedia\Rdbms\LoadBalancer->getServerConnection()
#2 /var/www/ar.wikivahdat.com/w/includes/libs/rdbms/database/DBConnRef.php(107): Wikimedia\Rdbms\LoadBalancer->getConnectionInternal()
#3 /var/www/ar.wikivahdat.com/w/includes/libs/rdbms/database/DBConnRef.php(125): Wikimedia\Rdbms\DBConnRef->ensureConnection()
#4 /var/www/ar.wikivahdat.com/w/includes/libs/rdbms/database/DBConnRef.php(338): Wikimedia\Rdbms\DBConnRef->__call()
#5 /var/www/ar.wikivahdat.com/w/includes/libs/rdbms/querybuilder/SelectQueryBuilder.php(762): Wikimedia\Rdbms\DBConnRef->selectField()
#6 /var/www/ar.wikivahdat.com/w/includes/language/LCStoreDB.php(65): Wikimedia\Rdbms\SelectQueryBuilder->fetchField()
#7 /var/www/ar.wikivahdat.com/w/includes/language/LocalisationCache.php(539): LCStoreDB->get()
#8 /var/www/ar.wikivahdat.com/w/includes/language/LocalisationCache.php(403): LocalisationCache->loadSubitem()
#9 /var/www/ar.wikivahdat.com/w/includes/language/LocalisationCache.php(419): LocalisationCache->getSubitem()
#10 /var/www/ar.wikivahdat.com/w/includes/language/MessageCache.php(1267): LocalisationCache->getSubitemWithSource()
#11 /var/www/ar.wikivahdat.com/w/includes/language/MessageCache.php(1209): MessageCache->getMessageForLang()
#12 /var/www/ar.wikivahdat.com/w/includes/language/MessageCache.php(1103): MessageCache->getMessageFromFallbackChain()
#13 /var/www/ar.wikivahdat.com/w/includes/Message/Message.php(1554): MessageCache->get()
#14 /var/www/ar.wikivahdat.com/w/includes/Message/Message.php(1036): MediaWiki\Message\Message->fetchMessage()
#15 /var/www/ar.wikivahdat.com/w/includes/Message/Message.php(1164): MediaWiki\Message\Message->format()
#16 /var/www/ar.wikivahdat.com/w/includes/Output/OutputPage.php(1214): MediaWiki\Message\Message->escaped()
#17 /var/www/ar.wikivahdat.com/w/includes/exception/MWExceptionRenderer.php(181): MediaWiki\Output\OutputPage->setPageTitleMsg()
#18 /var/www/ar.wikivahdat.com/w/includes/exception/MWExceptionRenderer.php(109): MWExceptionRenderer::reportHTML()
#19 /var/www/ar.wikivahdat.com/w/includes/exception/MWExceptionHandler.php(135): MWExceptionRenderer::output()
#20 /var/www/ar.wikivahdat.com/w/includes/exception/MWExceptionHandler.php(239): MWExceptionHandler::report()
#21 /var/www/ar.wikivahdat.com/w/includes/MediaWikiEntryPoint.php(222): MWExceptionHandler::handleException()
#22 /var/www/ar.wikivahdat.com/w/includes/actions/ActionEntryPoint.php(82): MediaWiki\MediaWikiEntryPoint->handleTopLevelError()
#23 /var/www/ar.wikivahdat.com/w/includes/MediaWikiEntryPoint.php(206): MediaWiki\Actions\ActionEntryPoint->handleTopLevelError()
#24 /var/www/ar.wikivahdat.com/w/index.php(58): MediaWiki\MediaWikiEntryPoint->run()
#25 {main}