A PHP Error was encountered

Severity: Notice

Message: Undefined index: username

Filename: admin/header.php

Line Number: 88

Backtrace:

File: /var/www/html/application/views/admin/header.php
Line: 88
Function: _error_handler

File: /var/www/html/application/controllers/admin/Bbk.php
Line: 25
Function: view

File: /var/www/html/index.php
Line: 318
Function: require_once