Try waiting a few minutes and reloading.
(Cannot access the database)
Backtrace:
#0 /var/www/html/includes/libs/rdbms/loadbalancer/LoadBalancer.php(897): Database->reportConnectionError('php_network_get...')
#1 /var/www/html/includes/libs/rdbms/loadbalancer/LoadBalancer.php(572): LoadBalancer->reportConnectionError()
#2 /var/www/html/includes/GlobalFunctions.php(3075): LoadBalancer->getConnection(0, Array, false)
#3 /var/www/html/includes/interwiki/ClassicInterwikiLookup.php(285): wfGetDB(-1)
#4 /var/www/html/includes/libs/objectcache/WANObjectCache.php(1004): MediaWiki\Interwiki\ClassicInterwikiLookup->MediaWiki\Interwiki\{closure}(false, 10800, Array, NULL)
#5 /var/www/html/includes/libs/objectcache/WANObjectCache.php(906): WANObjectCache->doGetWithSetCallback('wikidb-hzg_:int...', 10800, Object(Closure), Array)
#6 /var/www/html/includes/interwiki/ClassicInterwikiLookup.php(297): WANObjectCache->getWithSetCallback('wikidb-hzg_:int...', 10800, Object(Closure))
#7 /var/www/html/includes/interwiki/ClassicInterwikiLookup.php(154): MediaWiki\Interwiki\ClassicInterwikiLookup->load('\xD0\xB2\xD0\xB0\xD1\x80\xD0\xB4\xD0\xB0\xD0\xBD\xD1\x8F\xD0...')
#8 /var/www/html/includes/interwiki/ClassicInterwikiLookup.php(130): MediaWiki\Interwiki\ClassicInterwikiLookup->fetch('\xD0\xB2\xD0\xB0\xD1\x80\xD0\xB4\xD0\xB0\xD0\xBD\xD1\x8F\xD0...')
#9 /var/www/html/includes/interwiki/Interwiki.php(69): MediaWiki\Interwiki\ClassicInterwikiLookup->isValidInterwiki('\xD0\x92\xD0\xB0\xD1\x80\xD0\xB4\xD0\xB0\xD0\xBD\xD1\x8F\xD0...')
#10 /var/www/html/includes/title/MediaWikiTitleCodec.php(327): Interwiki::isValidInterwiki('\xD0\x92\xD0\xB0\xD1\x80\xD0\xB4\xD0\xB0\xD0\xBD\xD1\x8F\xD0...')
#11 /var/www/html/includes/Title.php(3366): MediaWikiTitleCodec->splitTitleString('\xD0\x92\xD0\xB0\xD1\x80\xD0\xB4\xD0\xB0\xD0\xBD\xD1\x8F\xD0...', 0)
#12 /var/www/html/includes/Title.php(352): Title->secureAndSplit()
#13 /var/www/html/includes/MediaWiki.php(80): Title::newFromURL('\xD0\x92\xD0\xB0\xD1\x80\xD0\xB4\xD0\xB0\xD0\xBD\xD1\x8F\xD0...')
#14 /var/www/html/includes/MediaWiki.php(136): MediaWiki->parseTitle()
#15 /var/www/html/includes/MediaWiki.php(766): MediaWiki->getTitle()
#16 /var/www/html/includes/MediaWiki.php(512): MediaWiki->main()
#17 /var/www/html/index.php(43): MediaWiki->run()
#18 {main}