Create a custom 404 page

The link's instructions did not work.

SEF = yes
URL Rewriting = yes
Add suffix = no

I got the code displaying on the screen.

My "hidden menu" alias to the custom 404 page is:

what-were-you-looking-for

So what do I change?

This worked:

Given this global configuration:
SEF = yes
URL Rewriting = yes
Add suffix = no

1. Create an Article

2. Create Hidden Menu Item pointing to the Article Save - copy the menu alias - example: "what-were-you-looking-for"

3. Modify error.php

Just after:

defined('JEXEC' or die;

Add this one line of code:

if (($this->error->getCode()) == '404') {header('Location: http://www.mydomain.org/what-were-you-looking-for');
exit;
}