Database connection failed!

Stack Trace:

File: /opt/lampp/htdocs/ojs2/classes/core/Application.inc.php line 38
Function: PKPApplication->PKPApplication()

File: /opt/lampp/htdocs/ojs2/lib/pkp/includes/bootstrap.inc.php line 59
Function: Application->Application()

File: /opt/lampp/htdocs/ojs2/index.php line 60
Function: require("/opt/lampp/htdocs/ojs2/lib/pkp/includes/bootstrap.inc.php")