Warning: PDO::__construct(): php_network_getaddresses: getaddrinfo failed: Temporary failure in name resolution in /var/www/html/include/db.php on line 10

Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[HY000] [2002] php_network_getaddresses: getaddrinfo failed: Temporary failure in name resolution' in /var/www/html/include/db.php:10 Stack trace: #0 /var/www/html/include/db.php(10): PDO->__construct('mysql:host=db;d...', 'user', 'password') #1 /var/www/html/include/sescheck.php(28): require_once('/var/www/html/i...') #2 /var/www/html/main.php(2): require_once('/var/www/html/i...') #3 {main} thrown in /var/www/html/include/db.php on line 10