A PHP Error was encountered

Severity: Notice

Message: Undefined index: HTTP_REFERER

Filename: controllers/Language.php

Line Number: 22

Backtrace:

File: D:\www\localuser\webmaster\2021\appsystem\web_modules\website\controllers\Language.php
Line: 22
Function: _error_handler

File: D:\www\localuser\webmaster\2021\appsystem\web_modules\website\controllers\Language.php
Line: 15
Function: change

File: D:\www\localuser\webmaster\2021\index.php
Line: 315
Function: require_once