Warning: mysqli_connect(): (HY000/2002): No such file or directory in /var/www/html/admin/mysqli.inc.php on line 36

Fatal error: Uncaught TypeError: mysqli_set_charset(): Argument #1 ($mysql) must be of type mysqli, false given in /var/www/html/admin/mysqli.inc.php:41 Stack trace: #0 /var/www/html/admin/mysqli.inc.php(41): mysqli_set_charset(false, 'utf8') #1 /var/www/html/common.inc.php(12): mysqliConnect() #2 /var/www/html/index.php(7): include('/var/www/html/c...') #3 {main} thrown in /var/www/html/admin/mysqli.inc.php on line 41