next.js: [NEXT-734] Revalidated page with notFound true does not return 404 Page

Verify canary release

• I verified that the issue exists in the latest Next.js canary release

Provide environment information

npx --no-install next info

    Operating System:
      Platform: linux
      Arch: x64
      Version: #32-Ubuntu SMP PREEMPT_DYNAMIC Fri Jan 20 15:20:08 UTC 2023
    Binaries:
      Node: 16.19.0
      npm: 8.19.3
      Yarn: 1.22.19
      pnpm: N/A
    Relevant packages:
      next: 13.2.2-canary.3
      eslint-config-next: 13.2.1
      react: 18.2.0
      react-dom: 18.2.0

Which area(s) of Next.js are affected? (leave empty if unsure)

No response

Link to the code that reproduces this issue

https://github.com/floreq/200-to-404

To Reproduce

1. Install project:

npm install

1. Build and run production application:

npm run build && npm run start

1. Go to http://localhost:3000/blog/1 page.
2. Make some page refreshes.
3. Spot that the page never become 404 Page when minutes are even.
   • In this example, when minutes are even is set notFound: true for Post Page.

Describe the Bug

When a page was correctly generated. Than when getStaticProps returns notFound: true for that page. The page is not removed from .next/server/pages. The page is still visible.

In the code to reproduce issue, when the page is revalidated with notFound: true on even minutes. x-nextjs-cache is set to STALE and stays that way. Even if refreshing the page.

• x-nextjs-cache changes only to HIT when the page is revalidated without notFound: true.

---

In next.config.js is set isrMemoryCacheSize: 0 to highlight this problem.

//next.config.js
module.exports = {
  [...]
  experimental: {
    isrMemoryCacheSize: 0,
  },
};

---

Image 1

• correctly loaded page, x-nextjs-cache: HIT, odd minutes

Image 2

• incorrectly loaded page, notFound: true, x-nextjs-cache: STALE, even minutes

Expected Behavior

When a page is successfully revalidated with notFound: true returned from getStaticProps:

1. the page should display 404 Page, not itself,
2. and the page should not be in .next/server/pages.

Which browser are you using? (if relevant)

No response

How are you deploying your application? (if relevant)

next start

_NEXT-734