A PHP Error was encountered

Severity: Notice

Message: Only variables should be passed by reference

Filename: controllers/Error_404.php

Line Number: 101

Backtrace:

File: /home/ubuntu/westernoverseas/web_and_langgraph_chatbot/application/controllers/Error_404.php
Line: 101
Function: _error_handler

File: /home/ubuntu/westernoverseas/web_and_langgraph_chatbot/index.php
Line: 309
Function: require_once