Try waiting a few minutes and reloading.
(Cannot access the database)
Backtrace:
#0 /var/www/html/includes/libs/rdbms/loadbalancer/LoadBalancer.php(956): Wikimedia\Rdbms\LoadBalancer->reportConnectionError() #1 /var/www/html/includes/libs/rdbms/loadbalancer/LoadBalancer.php(928): Wikimedia\Rdbms\LoadBalancer->getServerConnection() #2 /var/www/html/includes/libs/rdbms/loadbalancer/LoadBalancer.php(1086): Wikimedia\Rdbms\LoadBalancer->getConnection() #3 /var/www/html/includes/GlobalFunctions.php(2208): Wikimedia\Rdbms\LoadBalancer->getMaintenanceConnectionRef() #4 /var/www/html/includes/cache/localisation/LCStoreDB.php(57): wfGetDB() #5 /var/www/html/includes/cache/localisation/LocalisationCache.php(448): LCStoreDB->get() #6 /var/www/html/includes/cache/localisation/LocalisationCache.php(494): LocalisationCache->isExpired() #7 /var/www/html/includes/cache/localisation/LocalisationCache.php(370): LocalisationCache->initLanguage() #8 /var/www/html/includes/cache/localisation/LocalisationCache.php(311): LocalisationCache->loadItem() #9 /var/www/html/includes/language/Language.php(3147): LocalisationCache->getItem() #10 /var/www/html/includes/specialpage/SpecialPageFactory.php(1130): Language->getSpecialPageAliases() #11 /var/www/html/includes/specialpage/SpecialPageFactory.php(1189): MediaWiki\SpecialPage\SpecialPageFactory->getAliasList() #12 /var/www/html/includes/Title.php(1286): MediaWiki\SpecialPage\SpecialPageFactory->resolveAlias() #13 /var/www/html/includes/MediaWiki.php(211): Title->isSpecial() #14 /var/www/html/includes/MediaWiki.php(912): MediaWiki->performRequest() #15 /var/www/html/includes/MediaWiki.php(563): MediaWiki->main() #16 /var/www/html/index.php(53): MediaWiki->run() #17 /var/www/html/index.php(46): wfIndexMain() #18 {main}