`notFoundComponent` cannot be rendered on prerendered routes

[taroj1205]

Which project does this relate to?

Start

Describe the bug

Currently, if you access a 404 page in a fully prerendered app, it will not render anything.
I have deployed a static website on Cloudflare Pages, and there seemed to be no way to render a 404 in production.

On cloudflare pages, a 404.html in root will be used to render a not-found page.

https://developers.cloudflare.com/pages/configuration/serving-pages/#not-found-behavior

I have tried the following configuration to manually output a 404.html.

      prerender: {
        enabled: true,
        autoSubfolderIndex: true,
        crawlLinks: true,
      },
      pages: [
        {
          path: "/404",
          prerender: { enabled: true, outputPath: "/404.html" },
        },
      ],

If you access a non-existent page with JS disabled, you will see the 404 page, but with JS tanstack will hydrate with an empty page.

If you prerender a non-existent route with

        {
          path: "/this-route-doesnt-exist",
          prerender: {enabled: true}
        }

the build will fail (as expected), because you would want prerendering to fail if there was an error.

Maybe we should be able to configure in a way that we allow 404 to be prerendered?

Reproduction:
URL: https://tanstack-start-404.pages.dev/a
Actual 404 route: https://tanstack-start-404.pages.dev/404 (prerendered automatically from 404.tsx)
GitHub: https://github.com/taroj1205/tanstack-start-5427-not-found-component

Your Example Website or App

https://github.com/taroj1205/tanstack-start-404

Steps to Reproduce the Bug or Issue

1. Go to https://tanstack-start-404.pages.dev/a
2. See empty page

Expected behavior

As a user, I expect a not found component or 404.html being rendered.

Screenshots or Videos

JS Disabled:

JS Enabled:

Platform

• Router / Start Version: 1.132.0
• OS: Windows 11 (WSL)
• Browser: Helium
• Browser Version: Version 0.4.12.1 (Official Build, Chromium 140.0.7339.207)
• Bundler: vite
• Bundler Version: 7.1.7

Additional context

Conversation on discord: https://discord.com/channels/719702312431386674/1238170697650405547/1425979592010760274

[matclayton]

We've experienced what I think is a similar problem and have a proposed PR #5686 incase its any use

[birkskyum]

We've merged #5686 - @taroj1205 , would you mind checking if this issue is resolved?