A PHP Error was encountered

Severity: Notice

Message: Undefined index: HTTP_REFERER

Filename: controllers/RegisterController.php

Line Number: 91

Backtrace:

File: /opt/bitnami/apache2/htdocs/application/controllers/RegisterController.php
Line: 91
Function: _error_handler

File: /opt/bitnami/apache2/htdocs/index.php
Line: 293
Function: require_once