MediaWiki internal error.

Original exception: [7ed436e4c0602e691ae36821] /wiki/%241 Wikimedia\Rdbms\DBConnectionError from line 1423 of /var/www/production/w/includes/libs/rdbms/loadbalancer/LoadBalancer.php: Cannot access the database: Unknown error (localhost)
Backtrace:
#0 /var/www/production/w/includes/libs/rdbms/loadbalancer/LoadBalancer.php(937): Wikimedia\Rdbms\LoadBalancer->reportConnectionError()
#1 /var/www/production/w/includes/libs/rdbms/loadbalancer/LoadBalancer.php(904): Wikimedia\Rdbms\LoadBalancer->getServerConnection()
#2 /var/www/production/w/includes/libs/rdbms/loadbalancer/LoadBalancer.php(1049): Wikimedia\Rdbms\LoadBalancer->getConnection()
#3 /var/www/production/w/includes/GlobalFunctions.php(2463): Wikimedia\Rdbms\LoadBalancer->getMaintenanceConnectionRef()
#4 /var/www/production/w/includes/cache/localisation/LCStoreDB.php(56): wfGetDB()
#5 /var/www/production/w/includes/cache/localisation/LocalisationCache.php(449): LCStoreDB->get()
#6 /var/www/production/w/includes/cache/localisation/LocalisationCache.php(495): LocalisationCache->isExpired()
#7 /var/www/production/w/includes/cache/localisation/LocalisationCache.php(371): LocalisationCache->initLanguage()
#8 /var/www/production/w/includes/cache/localisation/LocalisationCache.php(312): LocalisationCache->loadItem()
#9 /var/www/production/w/includes/language/LanguageFallback.php(106): LocalisationCache->getItem()
#10 /var/www/production/w/includes/language/LanguageFactory.php(175): MediaWiki\Languages\LanguageFallback->getAll()
#11 /var/www/production/w/includes/language/LanguageFactory.php(121): MediaWiki\Languages\LanguageFactory->newFromCode()
#12 /var/www/production/w/includes/ServiceWiring.php(241): MediaWiki\Languages\LanguageFactory->getLanguage()
#13 /var/www/production/w/vendor/wikimedia/services/src/ServiceContainer.php(447): Wikimedia\Services\ServiceContainer->{closure}()
#14 /var/www/production/w/vendor/wikimedia/services/src/ServiceContainer.php(416): Wikimedia\Services\ServiceContainer->createService()
#15 /var/www/production/w/includes/MediaWikiServices.php(623): Wikimedia\Services\ServiceContainer->getService()
#16 /var/www/production/w/includes/Setup.php(700): MediaWiki\MediaWikiServices->getContentLanguage()
#17 /var/www/production/w/includes/WebStart.php(89): require_once(string)
#18 /var/www/production/w/index.php(44): require(string)
#19 {main}

Exception caught inside exception handler: [7ed436e4c0602e691ae36821] /wiki/%241 Wikimedia\Rdbms\DBConnectionError from line 1423 of /var/www/production/w/includes/libs/rdbms/loadbalancer/LoadBalancer.php: Cannot access the database: Unknown error (localhost)
Backtrace:
#0 /var/www/production/w/includes/libs/rdbms/loadbalancer/LoadBalancer.php(937): Wikimedia\Rdbms\LoadBalancer->reportConnectionError()
#1 /var/www/production/w/includes/libs/rdbms/loadbalancer/LoadBalancer.php(904): Wikimedia\Rdbms\LoadBalancer->getServerConnection()
#2 /var/www/production/w/includes/libs/rdbms/loadbalancer/LoadBalancer.php(1049): Wikimedia\Rdbms\LoadBalancer->getConnection()
#3 /var/www/production/w/includes/GlobalFunctions.php(2463): Wikimedia\Rdbms\LoadBalancer->getMaintenanceConnectionRef()
#4 /var/www/production/w/includes/cache/localisation/LCStoreDB.php(56): wfGetDB()
#5 /var/www/production/w/includes/cache/localisation/LocalisationCache.php(394): LCStoreDB->get()
#6 /var/www/production/w/includes/cache/localisation/LocalisationCache.php(312): LocalisationCache->loadItem()
#7 /var/www/production/w/includes/language/LanguageFallback.php(106): LocalisationCache->getItem()
#8 /var/www/production/w/includes/language/LanguageFactory.php(175): MediaWiki\Languages\LanguageFallback->getAll()
#9 /var/www/production/w/includes/language/LanguageFactory.php(121): MediaWiki\Languages\LanguageFactory->newFromCode()
#10 /var/www/production/w/includes/ServiceWiring.php(241): MediaWiki\Languages\LanguageFactory->getLanguage()
#11 /var/www/production/w/vendor/wikimedia/services/src/ServiceContainer.php(447): Wikimedia\Services\ServiceContainer->{closure}()
#12 /var/www/production/w/vendor/wikimedia/services/src/ServiceContainer.php(416): Wikimedia\Services\ServiceContainer->createService()
#13 /var/www/production/w/includes/MediaWikiServices.php(623): Wikimedia\Services\ServiceContainer->getService()
#14 /var/www/production/w/includes/ServiceWiring.php(694): MediaWiki\MediaWikiServices->getContentLanguage()
#15 /var/www/production/w/vendor/wikimedia/services/src/ServiceContainer.php(447): Wikimedia\Services\ServiceContainer->{closure}()
#16 /var/www/production/w/vendor/wikimedia/services/src/ServiceContainer.php(416): Wikimedia\Services\ServiceContainer->createService()
#17 /var/www/production/w/includes/MediaWikiServices.php(925): Wikimedia\Services\ServiceContainer->getService()
#18 /var/www/production/w/includes/exception/MWExceptionRenderer.php(329): MediaWiki\MediaWikiServices->getMessageCache()
#19 /var/www/production/w/includes/exception/MWExceptionRenderer.php(63): MWExceptionRenderer::reportOutageHTML()
#20 /var/www/production/w/includes/exception/MWExceptionHandler.php(106): MWExceptionRenderer::output()
#21 /var/www/production/w/includes/exception/MWExceptionHandler.php(185): MWExceptionHandler::report()
#22 /var/www/production/w/includes/exception/MWExceptionHandler.php(156): MWExceptionHandler::handleException()
#23 [internal function]: MWExceptionHandler::handleUncaughtException()
#24 {main}