A PHP Error was encountered

Severity: Notice

Message: Trying to get property 'id' of non-object

Filename: controllers/Exam.php

Line Number: 141

Backtrace:

File: /home/nhchuyo7/public_html/ba/controllers/Exam.php
Line: 141
Function: _error_handler

File: /home/nhchuyo7/public_html/ba/controllers/Exam.php
Line: 317
Function: UserID

File: /home/nhchuyo7/public_html/index.php
Line: 315
Function: require_once