A PHP Error was encountered

Severity: Notice

Message: Undefined index: HTTP_REFERER

Filename: controllers/Welcome.php

Line Number: 20

Backtrace:

File: D:\vhosts\ozgurmtc.com\httpdocs\application\controllers\Welcome.php
Line: 20
Function: _error_handler

File: D:\vhosts\ozgurmtc.com\httpdocs\index.php
Line: 315
Function: require_once