I’d like to know if you are implementing this because not-found.tsx wasn’t enough for you?

i tried that, but it was not working (or maybe I did something wrong), then implemented this approach

Fair enough.
The thing is that you need to explicitly call the notFound() function in order to trigger the not-found.tsx file per route segment. Otherwise the root not-found.tsx will be rendered in place of any routes that Next.js couldn't find.

are you saying I can only use:

// inside admin/not-found.js
export default function NotFound() {
  return ();

and not like:

export default function Abc() {
  return ();

....for all of my not-found.js files?

not-found.tsx files should export default a component, I don’t think the name matters much since default exports can take whatever name you want.

This component will be the fallback for those pages that weren’t found by Next.js at runtime. But only the not-found.tsx file at the very root will be displayed in these cases.

If you want to trigger route level specific not-found files you need to call the notFound() from the next/navigation package in order to render the route level fallback.

Makes sense?

Suppose this is my structure:

/app
  (dashboard)
    /admin
      /viewer
      /[...not-found]
      page.jsx
    /user
      /viewer
      /[...not-found]
      page.jsx
    /helper
      /viewer
      /[...not-found]
      page.jsx

you are saying I call notFound() in page.jsx of admin, user n helper. like:

import { notFound } from 'next/navigation'

//then I check if the route exists or not, if it doesn't, i call the notFound().

Basically