I have been asked to create a completely bespoke 404 error page.Looking at the error.php file, it's very basic. I've now created a successful custom_error PHP file, and can use this to overwrite the content of the error.php file to create the elegant 404 error page required.
The problem, of course, is that when Helix Ultimate is upgraded, the error.php file is overwritten back to the plain 404 page. I looked at the module insertion idea, but it simply didn't give the look and feel that was needed by the end user.
Can you investigate the possibility of using overrides somehow to ensure that the custom error file I've created is not overwritten?
Your advice is welcome.