Database connection failed!

Stack Trace:

File: /var/www/html/journals/classes/core/Application.inc.php line 29
Function: PKPApplication->PKPApplication()

File: /var/www/html/journals/lib/pkp/includes/bootstrap.inc.php line 58
Function: Application->Application()

File: /var/www/html/journals/index.php line 61
Function: require("/var/www/html/journals/lib/pkp/includes/bootstrap.inc.php")