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(413): LocalisationCache->initLanguage() #8 /var/www/html/includes/cache/localisation/LocalisationCache.php(332): LocalisationCache->loadSubitem() #9 /var/www/html/includes/language/Language.php(2607): LocalisationCache->getSubitem() #10 /var/www/html/includes/cache/MessageCache.php(1053): Language->getMessage() #11 /var/www/html/includes/cache/MessageCache.php(1011): MessageCache->getMessageForLang() #12 /var/www/html/includes/cache/MessageCache.php(953): MessageCache->getMessageFromFallbackChain() #13 /var/www/html/includes/language/Message.php(1491): MessageCache->get() #14 /var/www/html/includes/language/Message.php(968): Message->fetchMessage() #15 /var/www/html/includes/language/Message.php(1071): Message->format() #16 /var/www/html/includes/api/ApiErrorFormatter_BackCompat.php(90): Message->text() #17 /var/www/html/includes/api/ApiErrorFormatter.php(175): ApiErrorFormatter_BackCompat->addWarningOrError() #18 /var/www/html/includes/api/ApiMain.php(1366): ApiErrorFormatter->addError() #19 /var/www/html/includes/api/ApiMain.php(932): ApiMain->substituteResultWithError() #20 /var/www/html/includes/api/ApiMain.php(877): ApiMain->handleException() #21 /var/www/html/includes/api/ApiMain.php(841): ApiMain->executeActionWithErrorHandling() #22 /var/www/html/api.php(90): ApiMain->execute() #23 /var/www/html/api.php(45): wfApiMain() #24 {main}