Try waiting a few minutes and reloading.
(Cannot access the database)
Backtrace:
#0 /var/www/html/wiki/includes/libs/rdbms/loadbalancer/LoadBalancer.php(769): Wikimedia\Rdbms\LoadBalancer->reportConnectionError() #1 /var/www/html/wiki/includes/page/WikiPage.php(477): Wikimedia\Rdbms\LoadBalancer->getConnection(0) #2 /var/www/html/wiki/includes/page/WikiPage.php(590): WikiPage->loadPageData() #3 /var/www/html/wiki/includes/page/WikiPage.php(631): WikiPage->exists() #4 /var/www/html/wiki/includes/page/WikiPage.php(269): WikiPage->getContentModel() #5 /var/www/html/wiki/includes/page/WikiPage.php(256): WikiPage->getContentHandler() #6 /var/www/html/wiki/includes/actions/Action.php(98): WikiPage->getActionOverrides() #7 /var/www/html/wiki/includes/actions/Action.php(156): Action::factory('view', Object(WikiCategoryPage), Object(RequestContext)) #8 /var/www/html/wiki/includes/MediaWiki.php(155): Action::getActionName(Object(RequestContext)) #9 /var/www/html/wiki/includes/MediaWiki.php(777): MediaWiki->getAction() #10 /var/www/html/wiki/includes/MediaWiki.php(517): MediaWiki->main() #11 /var/www/html/wiki/index.php(42): MediaWiki->run() #12 {main}