Does Next always deploy a /404 and /500 static route that are always available?

[tommhuth]

I noticed something unexpected on a project, where it looks like Next's default error pages for 404 and 500 are deployed as hard coded routes that can be access on root directly: /500 and /400 both return the Nextjs default error pages together with their status code. This happens in a fairly large project where all routes are grouped under a [locale] segment (this is also where the custom error pages are located).

As I was debugging this I tried a simpler project (all static pages with no i18n), and here the 500 error page still shows up when going to /500 (see https://kompassterapeutene.vercel.app/500), but the 404 page does not give me the default 404 error page but my own custom 404 (cf to the previous project where it is always the default Next error styling).

Is this to be expected? Should the error pages be moved to the root of the app folder to ensure it is used constantly? I tried this, and it made no difference for the first project mentioned.