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/GlobalFunctions.php(2694): Wikimedia\Rdbms\LoadBalancer->getConnection(0, Array, false) #2 /var/www/html/wiki/includes/Title.php(428): wfGetDB(-1) #3 /var/www/html/wiki/includes/MediaWiki.php(81): Title::newFromID(3797) #4 /var/www/html/wiki/includes/MediaWiki.php(140): MediaWiki->parseTitle() #5 /var/www/html/wiki/includes/MediaWiki.php(776): MediaWiki->getTitle() #6 /var/www/html/wiki/includes/MediaWiki.php(517): MediaWiki->main() #7 /var/www/html/wiki/index.php(42): MediaWiki->run() #8 {main}