A PHP Error was encountered

Severity: Notice

Message: Undefined index: HTTP_REFERER

Filename: helpers/common_helper.php

Line Number: 204

Backtrace:

File: /home/ec2-user/pwk-renewal/application/helpers/common_helper.php
Line: 204
Function: _error_handler

File: /home/ec2-user/pwk-renewal/application/controllers/Project.php
Line: 92
Function: history_back_on_pwk

File: /home/ec2-user/pwk-renewal/index.php
Line: 315
Function: require_once