MediaWiki internal error.

Original exception: [ZgV4cCp4YRdrFRwgJpdNFQAAAAU] /index.php?title=Others&printable=yes mysqli_sql_exception from line 115 of /opt/web/wiki/common/includes/libs/rdbms/database/DatabaseMysqli.php: Connexion refusée
Backtrace:
#0 /opt/web/wiki/common/includes/libs/rdbms/database/DatabaseMysqli.php(115): mysqli->real_connect()
#1 /opt/web/wiki/common/includes/libs/rdbms/database/DatabaseMysqlBase.php(131): Wikimedia\Rdbms\DatabaseMysqli->mysqlConnect()
#2 /opt/web/wiki/common/includes/libs/rdbms/database/Database.php(285): Wikimedia\Rdbms\DatabaseMysqlBase->open()
#3 /opt/web/wiki/common/includes/libs/rdbms/database/DatabaseMysqlBase.php(102): Wikimedia\Rdbms\Database->__construct()
#4 /opt/web/wiki/common/includes/libs/rdbms/database/Database.php(415): Wikimedia\Rdbms\DatabaseMysqlBase->__construct()
#5 /opt/web/wiki/common/includes/libs/rdbms/loadbalancer/LoadBalancer.php(985): Wikimedia\Rdbms\Database::factory()
#6 /opt/web/wiki/common/includes/libs/rdbms/loadbalancer/LoadBalancer.php(801): Wikimedia\Rdbms\LoadBalancer->reallyOpenConnection()
#7 /opt/web/wiki/common/includes/libs/rdbms/loadbalancer/LoadBalancer.php(667): Wikimedia\Rdbms\LoadBalancer->openConnection()
#8 /opt/web/wiki/common/includes/GlobalFunctions.php(2858): Wikimedia\Rdbms\LoadBalancer->getConnection()
#9 /opt/web/wiki/common/includes/page/WikiPage.php(386): wfGetDB()
#10 /opt/web/wiki/common/includes/page/WikiPage.php(470): WikiPage->loadPageData()
#11 /opt/web/wiki/common/includes/page/WikiPage.php(511): WikiPage->exists()
#12 /opt/web/wiki/common/includes/page/WikiPage.php(232): WikiPage->getContentModel()
#13 /opt/web/wiki/common/includes/page/WikiPage.php(219): WikiPage->getContentHandler()
#14 /opt/web/wiki/common/includes/actions/Action.php(96): WikiPage->getActionOverrides()
#15 /opt/web/wiki/common/includes/actions/Action.php(154): Action::factory()
#16 /opt/web/wiki/common/includes/MediaWiki.php(155): Action::getActionName()
#17 /opt/web/wiki/common/includes/MediaWiki.php(768): MediaWiki->getAction()
#18 /opt/web/wiki/common/includes/MediaWiki.php(523): MediaWiki->main()
#19 /opt/web/wiki/en/index.php(43): MediaWiki->run()
#20 {main}

Exception caught inside exception handler: [ZgV4cCp4YRdrFRwgJpdNFQAAAAU] /index.php?title=Others&printable=yes mysqli_sql_exception from line 115 of /opt/web/wiki/common/includes/libs/rdbms/database/DatabaseMysqli.php: Connexion refusée
Backtrace:
#0 /opt/web/wiki/common/includes/libs/rdbms/database/DatabaseMysqli.php(115): mysqli->real_connect()
#1 /opt/web/wiki/common/includes/libs/rdbms/database/DatabaseMysqlBase.php(131): Wikimedia\Rdbms\DatabaseMysqli->mysqlConnect()
#2 /opt/web/wiki/common/includes/libs/rdbms/database/Database.php(285): Wikimedia\Rdbms\DatabaseMysqlBase->open()
#3 /opt/web/wiki/common/includes/libs/rdbms/database/DatabaseMysqlBase.php(102): Wikimedia\Rdbms\Database->__construct()
#4 /opt/web/wiki/common/includes/libs/rdbms/database/Database.php(415): Wikimedia\Rdbms\DatabaseMysqlBase->__construct()
#5 /opt/web/wiki/common/includes/libs/rdbms/loadbalancer/LoadBalancer.php(985): Wikimedia\Rdbms\Database::factory()
#6 /opt/web/wiki/common/includes/libs/rdbms/loadbalancer/LoadBalancer.php(801): Wikimedia\Rdbms\LoadBalancer->reallyOpenConnection()
#7 /opt/web/wiki/common/includes/libs/rdbms/loadbalancer/LoadBalancer.php(667): Wikimedia\Rdbms\LoadBalancer->openConnection()
#8 /opt/web/wiki/common/includes/GlobalFunctions.php(2858): Wikimedia\Rdbms\LoadBalancer->getConnection()
#9 /opt/web/wiki/common/includes/cache/MessageCache.php(471): wfGetDB()
#10 /opt/web/wiki/common/includes/cache/MessageCache.php(426): MessageCache->loadFromDB()
#11 /opt/web/wiki/common/includes/cache/MessageCache.php(350): MessageCache->loadFromDBWithLock()
#12 /opt/web/wiki/common/includes/cache/MessageCache.php(991): MessageCache->load()
#13 /opt/web/wiki/common/includes/cache/MessageCache.php(918): MessageCache->getMsgFromNamespace()
#14 /opt/web/wiki/common/includes/cache/MessageCache.php(888): MessageCache->getMessageForLang()
#15 /opt/web/wiki/common/includes/cache/MessageCache.php(825): MessageCache->getMessageFromFallbackChain()
#16 /opt/web/wiki/common/includes/Message.php(1257): MessageCache->get()
#17 /opt/web/wiki/common/includes/Message.php(842): Message->fetchMessage()
#18 /opt/web/wiki/common/includes/Message.php(934): Message->toString()
#19 /opt/web/wiki/common/includes/OutputPage.php(950): Message->text()
#20 /opt/web/wiki/common/includes/OutputPage.php(995): OutputPage->setHTMLTitle()
#21 /opt/web/wiki/common/includes/OutputPage.php(2478): OutputPage->setPageTitle()
#22 /opt/web/wiki/common/includes/exception/MWExceptionRenderer.php(126): OutputPage->prepareErrorPage()
#23 /opt/web/wiki/common/includes/exception/MWExceptionRenderer.php(54): MWExceptionRenderer::reportHTML()
#24 /opt/web/wiki/common/includes/exception/MWExceptionHandler.php(75): MWExceptionRenderer::output()
#25 /opt/web/wiki/common/includes/exception/MWExceptionHandler.php(130): MWExceptionHandler::report()
#26 /opt/web/wiki/common/includes/MediaWiki.php(550): MWExceptionHandler::handleException()
#27 /opt/web/wiki/en/index.php(43): MediaWiki->run()
#28 {main}