I had a difficult time solving this bug, and finally solved it. I'm posting it here to help others who might be struggling with the same situation.
Code Source:
This code is from the Simple PHP Login System, Lesson 17 & 18.
My Setup:
Machine: Windows 10
WAMP
PHP version: 7.4.9
Code Editor: VS Code
Here is my error notice:
Notice: Only variables should be passed by reference in C:\wamp64\www\phplogin-parts17-18-projectfiles\register.php on line 144
I got that error message when I tried to register a member.
The problem lies in LI