nitro + spa mode breaks since v1.138.0

[ImSingee]

Which project does this relate to?

Start

Describe the bug

If you use nitro + spa mode, the vite build will report this error:

✓ built in 535ms
[prerender] Prerendering pages...
error during build:
Error: Failed to start the Vite preview server for prerendering
    at startPreviewServer (file:///project-dir/node_modules/.pnpm/@tanstack+start-plugin-core@1.139.6_@tanstack+react-router@1.139.6_react-dom@19.2.0_rea_4811f95400dc016e184359a72f378162/node_modules/@tanstack/start-plugin-core/dist/esm/prerender.js:195:11)
    at async prerender (file:///project-dir/node_modules/.pnpm/@tanstack+start-plugin-core@1.139.6_@tanstack+react-router@1.139.6_react-dom@19.2.0_rea_4811f95400dc016e184359a72f378162/node_modules/@tanstack/start-plugin-core/dist/esm/prerender.js:42:25)
    at async postServerBuild (file:///project-dir/node_modules/.pnpm/@tanstack+start-plugin-core@1.139.6_@tanstack+react-router@1.139.6_react-dom@19.2.0_rea_4811f95400dc016e184359a72f378162/node_modules/@tanstack/start-plugin-core/dist/esm/post-server-build.js:38:5)
    at async BasicMinimalPluginContext.handler (file:///project-dir/node_modules/.pnpm/@tanstack+start-plugin-core@1.139.6_@tanstack+react-router@1.139.6_react-dom@19.2.0_rea_4811f95400dc016e184359a72f378162/node_modules/@tanstack/start-plugin-core/dist/esm/plugin.js:267:11)
    at async Object.buildApp (file:///project-dir/node_modules/.pnpm/vite@7.2.4_@types+node@24.10.1_jiti@2.6.1_lightningcss@1.30.2_sugarss@5.0.1_postcss@8.5.6__tsx@4.20.6_yaml@2.8.1/node_modules/vite/dist/node/chunks/config.js:34542:5)
    at async CAC.<anonymous> (file:///project-dir/node_modules/.pnpm/vite@7.2.4_@types+node@24.10.1_jiti@2.6.1_lightningcss@1.30.2_sugarss@5.0.1_postcss@8.5.6__tsx@4.20.6_yaml@2.8.1/node_modules/vite/dist/node/cli.js:629:3)                                                                                                                                                                  
 ELIFECYCLE  Command failed with exit code 1.

Your Example Website or App

https://github.com/ImSingee/tanstack-start-bug-reproduce-for-spa

Steps to Reproduce the Bug or Issue

1. Setup nitro with tanstack start (https://tanstack.com/start/latest/docs/framework/react/guide/hosting#nitro)
2. Enable SPA mode (https://tanstack.com/start/latest/docs/framework/react/guide/spa-mode)

Expected behavior

Build should be success

Screenshots or Videos

No response

Platform

• Router / Start Version: 1.139.6
• OS: macOS
• Bundler: vite
• Bundler Version: ^7.2.4

Additional context

I created a bug-reproduce repo with the latest version, but I can confirm the issue starts at v1.138.0 after #5921 is merged.

After executing the pnpm build (failed), then execute npx vite preview, this error occurs:

error when starting preview server:
Error: Cannot load nitro build info. Make sure to build first.
    at BasicMinimalPluginContext.error (file:///project-dir/node_modules/.pnpm/vite@7.2.4_@types+node@22.19.1_jiti@2.6.1_lightningcss@1.30.2_tsx@4.20.6/node_modules/vite/dist/node/chunks/config.js:29511:35)
    at BasicMinimalPluginContext.configurePreviewServer (file:///project-dir/node_modules/.pnpm/nitro@3.0.1-alpha.1_rollup@4.53.3_vite@7.2.4_@types+node@22.19.1_jiti@2.6.1_lightningcss@1.30.2_tsx@4.20.6_/node_modules/nitro/dist/_build/vite.plugin.mjs:443:31)
    at async preview (file:///project-dir/node_modules/.pnpm/vite@7.2.4_@types+node@22.19.1_jiti@2.6.1_lightningcss@1.30.2_tsx@4.20.6/node_modules/vite/dist/node/chunks/config.js:35765:93)
    at async CAC.<anonymous> (file:///project-dir/node_modules/.pnpm/vite@7.2.4_@types+node@22.19.1_jiti@2.6.1_lightningcss@1.30.2_tsx@4.20.6/node_modules/vite/dist/node/cli.js:669:18)

[CarlosZiegler]

hey I have same issue with nitro and this looks like broke when using nit "nitro": "^3.0.1-alpha.1" when switch back to @tanstack/nitro-v2-vite-plugin this works as expectd:

Output "nitro": "^3.0.1-alpha.1":

Output "@tanstack/nitro-v2-vite-plugin": "^1.139.0":

[assarbertil]

I had this issue as well for a few hours but only when building on vercel, not locally.

I am also using SPA-mode and nitro v3 preview.

My error in vercel build logs:

[prerender] Prerendering pages...
error during build:
Error: Failed to start the Vite preview server for prerendering
    at startPreviewServer (file:///vercel/path0/node_modules/.bun/@tanstack+start-plugin-core@1.139.3+455187427322a990/node_modules/@tanstack/start-plugin-core/dist/esm/prerender.js:195:11)
    at async prerender (file:///vercel/path0/node_modules/.bun/@tanstack+start-plugin-core@1.139.3+455187427322a990/node_modules/@tanstack/start-plugin-core/dist/esm/prerender.js:42:25)
    at async postServerBuild (file:///vercel/path0/node_modules/.bun/@tanstack+start-plugin-core@1.139.3+455187427322a990/node_modules/@tanstack/start-plugin-core/dist/esm/post-server-build.js:38:5)
    at async BasicMinimalPluginContext.handler (file:///vercel/path0/node_modules/.bun/@tanstack+start-plugin-core@1.139.3+455187427322a990/node_modules/@tanstack/start-plugin-core/dist/esm/plugin.js:267:11)
    at async Object.buildApp (file:///vercel/path0/node_modules/.bun/vite@7.2.4+fad1561be79d52d9/node_modules/vite/dist/node/chunks/config.js:34542:5)
    at async CAC.<anonymous> (file:///vercel/path0/node_modules/.bun/vite@7.2.4+fad1561be79d52d9/node_modules/vite/dist/node/cli.js:629:3)
error: script "build" exited with code 1
Error: Command "bun run build" exited with 1

I resolved it by downgrading all the router and start packages to 1.136.18

"@tanstack/react-router": "1.136.18",
"@tanstack/react-router-devtools": "1.136.18",
"@tanstack/react-router-ssr-query": "1.136.18",
"@tanstack/react-start": "1.136.18",

It isn't a real solution but i cant spend any more time on it.

For me using the @tanstack/nitro-v2-vite-plugin raised another issue but i could see that being a workaround for some people.

[warkanum]

I'm also getting the same issue. Doing the downgrade fixes it. Happens on nitro + spa on version >1.136 for me too.