500 Internal Server Error during ISR with generateStaticParams

[tarunkhurana]

Summary

We are observing a 500 Internal Server Error in a Next.js 14 (App Router) project during ISR (Incremental Static Regeneration).
The error occurs inconsistently when a page uses generateStaticParams() returns an empty array, combined with data fetched from a CMS if anything coming invalid it is crashing a page. We are expecting a Error.tsx to appear or some custom error appear instead of nextjs internal server page. I did not find anywhere where we can customize this as well.
We also observed the same component works fine when rendered via SSR and it shows Error.tsx

Is this a known limitation with ISR + generateStaticParams([]) in App Router? How can we fix that?

Additional information

No response

Example

No response

[icyJoseph]

Can you explain a bit more, how this happening in a timeline? When you return empty params in your App Router version, and you allow new pages at runtime, the ISR would only show error, if it has to block to generate the page, and that itself errored. How does your file system tree look like?

[tarunkhurana]

Hi @icyJoseph I’ve attached a sample test application (testapp) to demonstrate the issue.
Inside the app directory, there are two folders:

app/products → contains a dynamic route that uses ISR (revalidate + generateStaticParams).

app/no-error-products → contains a dynamic route that uses SSR (with revalidation).

If you build and start the application, and then directly open:

http://localhost:3000/products/1
→ this route throws a 500 Internal Server Error because there is some mistake the property tsdtitle.sadas not exists, even though an error.tsx file exists.

http://localhost:3000/no-error-products/1
→ this route renders successfully and same error exists what we have in above but it shows error.tsx file

This test app is just a simplified example to illustrate the behavior, but our real production application follows a similar pattern — where all pages are ISR-based, using both generateStaticParams and revalidate together in page.tsx across multiple nested folders.

test-app.zip

[icyJoseph]

can you copy the project into a Stackblitz? I ain't gonna download a zip I can't see the source code for 😅

[tarunkhurana]

can you copy the project into a Stackblitz? I ain't gonna download a zip I can't see the source code for 😅

Hi @icyJoseph Here is the link https://stackblitz.com/edit/nextjs-wavd2enq
You will be able to replicate the same error when you do yarn build and yarn start and not in dev mode.

[tarunkhurana]

Hi @icyJoseph Sorry to bother you again. Did you get a chance to look into this?