GetStaticProps returning initial notFound never triggers a rebuild on revalidate with dynamic routes

[alizeait]

What version of Next.js are you using?

10.0.5

What version of Node.js are you using?

12.13.0

What browser are you using?

Chrome

What operating system are you using?

Windows

How are you deploying your application?

next start

Describe the Bug

If getStaticProps returns notFound: true in the initial build with a revalidate value, Nextjs never tries to rebuild the page

Expected Behavior

Nextjs should try rebuilding the page instead of assuming permanent 404

To Reproduce

export const getStaticProps = async (props) => {
  try {
    const dictionaries = await apiFetch();
    return {
      props: {
        dictionaries,
      },
      revalidate: 60,
    };
  } catch (error) {
// assume the api fetch fails with the initial build
   return {
      notFound: true,
      props: {
        dictionaries: {},
      },
      revalidate: 60,
    };
  }

// On subsequent re-builds after revalidate has passed and the api returns a ok response, Nextjs never tries to rebuild the page and always returns the 404 page instead

[janus-reith]

I actually observe the opposite behavior, here is a sandbox:
https://codesandbox.io/s/awesome-greider-11ugg
(Not sure though if your try/catch block might make a difference.)

You might need to fork and restart the sandbox to see it, it runs rimraf .next on start to ensure there is no cached content as I was unsure if something might get cached from previous runs otherwise.

If I return notFound: true in getStaticProps, it actually builds the page right on demand during runtime, and doesnt serve any stale page from build time, which is great for a usecase I have, where Static generation should happen after the build only.

I'm wondering however if that behavior of notFound during build is intended to work this way and meant to stay or just some sideeffect - I'm unable to find any documentation about notFound during build.

**Edit: ** Created a separate issue here: #21809

[alizeait]

Thanks for the sandbox @janus-reith, I actually forgot to mention that this happens with dynamic routes, I think how static routes work like in your Sandbox should be the way to go. I made a fork of your sandbox here with dynamic routes. Notice that the /intl/docs/intl-page always serves the 404 page even after revalidate time has passed since it errors during build while /us/docs/us-page page works as intended.

[bscaspar]

I am encountering a similar experience (but somewhat in reverse).

The initial static page with a dynamic route is built successfully. getStaticPaths uses {fallback: 'blocking'} and getStaticProps uses {revalidate: 1}. Then then the page data is removed from the db so getStaticProps returns {notFound: true}. Despite all this, the static page continues to be served.

I confirmed that the data fetching call that should happen in getStaticProps returns no data, so it appears as though getStaticProps isn't running at all.

[jatbone]

Same here, when {notFound: true} revalidate doesn't happen. Is this gonna be fixed soon? It's pretty big issue. Thanks

[lotharvm]

Any update on this? Also experiencing this and especially with dynamic routes being controlled by a client it's impossible to manually keep track of all the routes that change from/to 404..

[ramiel]

Same here, when a page is 404 it never gets rebuilt.