404/Not found component not rendering on dev server

[gabenddos]

Which project does this relate to?

Start

Describe the bug

I was writing the e2e tests for my application and I noticed that in production the Not found test worked fine but when using the dev command to run the tests it was breaking on the test.

❌ vite dev:

✅ But in production the component is rendering normally as it is supossed to be:

❌

• I was using Bun, but with a brand new Node, the issue still happens.
• The error just happens in vite dev.

✅

• After building the project and running with node ./output/server/index.mjs it works fine.
• I also noticed that commenting out the nitro plugin on vite.config.ts then running vite dev the not found component starts working again.

Your Example Website or App

https://github.com/gabenddos/tanstack-start-not-found-dev-error

Steps to Reproduce the Bug or Issue

1. Scaffolding a brand new Tanstack Start project
2. Setup the notFoundComponent (on router or any specific route you want) e.g. src/router.tsx

const router = createRouter({
	routeTree,
	context: {
		...rqContext,
	},
	defaultNotFoundComponent: () => <div>Not Found</div>, // ADDED NOT FOUND COMPONENT
	defaultPreload: "intent",
});

3. Runs the dev server with pnpm dev or bun dev.
4. Access any non existing route: e.g. http://localhost:3000/non-exising-route or /lorem-ipsum, etc...
   "Cannot Get /{pathname}" instead of the actual react not found component

Expected behavior

Should render react not found component instead of a Cannot Get error page.

Screenshots or Videos

No response

Platform

• Router / Start Version: ^1.132
• OS: macOS
• Browser: Chrome
• Browser Version: 143 (latest stable)
• Bundler: Vite
• Bundler Version: 7.1.7

Additional context

Stack blitz does not seams to reproduce the error, please clone the repo and run locally.
Related issue: #5960 Throwing a notFound on loaders seams to have the same bahaviour described in this issue

[zotodev]

Happened with me as well.

However I found that for my older project where I was using Nitro v2 instead of v3 its working fine, not sure if it relates to this.

[schiller-manuel]

this is fixed in nitro, but not released yet beyond the nightly track
use it like this:

"nitro": "npm:nitro-nightly@latest"

[gabenddos]

Thank you very much Schiller, your the real OG

I was already using nitro v3, (nitro v2 seem to not work properly with bun).

Using the "nitro": "npm:nitro-nightly@latest" on devDependencies of my package.json worked