Error page ignoring error_template changes

[LaocheXe]

501st website has been up for about 3 years now, using my defaitnzstrap3 theme - I have a custom 404 page set up in the theme templates. (I do keep the files up to date with Github).

New site using github files - working on a new theme, using error_template.php in the theme's/templates folder - however, it's not working.

I've even tried replacing e107_core/templates/error_template.php with my own - still same thing. I've cleared my browser cache, website cache, and tried it on other PC's and web browsers (Firefox, Chrome, Opera GX).

I even tried applying the 501st error_template to the new site, still no changes. error.php hasn't been updated in 2 years, 3 years for the error_template.php. I don't know what the issue is.

[LaocheXe]

I've even tried editing e107_handlers/error_page_class.php (edit the setPageNotFound() (404) - tried replacing the LAN's with regular text, nothing.

[CaMer0n]

The first site returns a 404 header.
The second site returns a 501 header.

Still digging..

[CaMer0n]

Solved. .htaccess was missing, so a 501 was returned.