v3: Cannot build TanStack Start pnpm monorepo in SPA mode with Nitro

Environment

node: 22.18.0
nitro: nitro-nightly@3.0.1-20251105-152910-c0ee44bf

Reproduction

https://github.com/rohanajayjain/ts-start-bug

Describe the bug

Trying to build in a pnpm monorepo using TanStack Start and Better Auth in SPA mode with nitro fails.

This seems to be specifically a nitro related issue as building without the nitro plugin works.

With SPA mode disabled, nitro can build the code without errors. We can then run node --env-file=.env .output/server/index.mjs as well without issue.

I've tried without adding ssr: { external: ["pg"] } and with it and get different logs (included below).

Without adding ssr: { external: ["pg"] }, we get ReferenceError: Cannot access 'pg' before initialization.

With [ssr](ssr: { external: ["pg"] }), we get Error [ERR_MODULE_NOT_FOUND]: Cannot find package 'pg' imported from /home/codebench/Dev/ts-start-bug/apps/web/.nitro/vite/services/ssr/assets/router-w0xdFAbu.js
Did you mean to import "pg/lib/index.js"?

Additional context

No response

Logs

When ssr external isn't set:

codebench@codebench:~/Dev/ts-start-bug/apps/web$ pnpm build

> web@0.0.1 build /home/codebench/Dev/ts-start-bug/apps/web
> vite build

vite v7.2.0 building client environment for production...
✓ 204 modules transformed.
.output/public/assets/index-DtR-hLxC.js    0.66 kB │ gzip:   0.41 kB
.output/public/assets/main-Dh3ZPKv-.js   352.12 kB │ gzip: 111.39 kB
✓ built in 977ms
vite v7.2.0 building ssr environment for production...
✓ 767 modules transformed.
.nitro/vite/services/ssr/assets/start-HYkvq4Ni.js                             0.06 kB
.nitro/vite/services/ssr/assets/_tanstack-start-manifest_v-B07cSHf9.js        0.45 kB
.nitro/vite/services/ssr/assets/index-DndBZZAl.js                             1.37 kB
.nitro/vite/services/ssr/assets/bun-sqlite-dialect-B2O0-0JW-DZaXpg95.js       4.72 kB
.nitro/vite/services/ssr/assets/node-sqlite-dialect-5DWxxNaH-CXgDQ1bH.js      4.74 kB
.nitro/vite/services/ssr/assets/index-n0yJTA-g.js                             6.41 kB
.nitro/vite/services/ssr/assets/index-y4iGJYqZ.js                             8.27 kB
.nitro/vite/services/ssr/server.js                                          116.39 kB
.nitro/vite/services/ssr/assets/router-ugILWlS3.js                        1,819.28 kB
✓ built in 2.08s
[prerender] Prerendering pages...
[prerender] Concurrency: 8
[prerender] Crawling: /
ReferenceError: Cannot access 'pg' before initialization
    at get default (file:///home/codebench/Dev/ts-start-bug/apps/web/.nitro/vite/services/ssr/assets/router-ugILWlS3.js:59:5)
    ... 8 lines matching cause stack trace ...
    at async file:///home/codebench/Dev/ts-start-bug/node_modules/.pnpm/@tanstack+start-plugin-core@1.134.12_@tanstack+react-router@1.134.12_react-dom@19.2.0_r_967f5b275724ce77a0f689c31de802f9/node_modules/@tanstack/start-plugin-core/dist/esm/queue.js:38:17 {
  cause: ReferenceError: Cannot access 'pg' before initialization
      at get default (file:///home/codebench/Dev/ts-start-bug/apps/web/.nitro/vite/services/ssr/assets/router-ugILWlS3.js:59:5)
      at getAugmentedNamespace (file:///home/codebench/Dev/ts-start-bug/apps/web/.nitro/vite/services/ssr/assets/router-ugILWlS3.js:47956:13)
      at file:///home/codebench/Dev/ts-start-bug/apps/web/.nitro/vite/services/ssr/assets/router-ugILWlS3.js:52097:36
      at ModuleJob.run (node:internal/modules/esm/module_job:343:25)
      at async onImport.tracePromise.__proto__ (node:internal/modules/esm/loader:647:26)
      at async getEntries (file:///home/codebench/Dev/ts-start-bug/apps/web/.nitro/vite/services/ssr/server.js:3263:21)
      at async startRequestResolver (file:///home/codebench/Dev/ts-start-bug/apps/web/.nitro/vite/services/ssr/server.js:3320:33)
      at async localFetch (file:///home/codebench/Dev/ts-start-bug/node_modules/.pnpm/@tanstack+start-plugin-core@1.134.12_@tanstack+react-router@1.134.12_react-dom@19.2.0_r_967f5b275724ce77a0f689c31de802f9/node_modules/@tanstack/start-plugin-core/dist/esm/prerender.js:63:22)
      at async file:///home/codebench/Dev/ts-start-bug/node_modules/.pnpm/@tanstack+start-plugin-core@1.134.12_@tanstack+react-router@1.134.12_react-dom@19.2.0_r_967f5b275724ce77a0f689c31de802f9/node_modules/@tanstack/start-plugin-core/dist/esm/prerender.js:125:23
      at async file:///home/codebench/Dev/ts-start-bug/node_modules/.pnpm/@tanstack+start-plugin-core@1.134.12_@tanstack+react-router@1.134.12_react-dom@19.2.0_r_967f5b275724ce77a0f689c31de802f9/node_modules/@tanstack/start-plugin-core/dist/esm/queue.js:38:17,
  status: 500,
  statusText: undefined,
  headers: undefined,
  data: undefined,
  body: undefined,
  unhandled: true
}
[prerender] Prerendered 0 pages:
[sitemap] Hint: Pages found, but no sitemap host has been set. To enable sitemap generation, set the `sitemap.host` option.

[nitro 10:56:32 am] ◐ Building [Nitro] (preset: node-server, compatibility: 2025-11-06)
file:///home/codebench/Dev/ts-start-bug/node_modules/.pnpm/@tanstack+start-plugin-core@1.134.12_@tanstack+react-router@1.134.12_react-dom@19.2.0_r_967f5b275724ce77a0f689c31de802f9/node_modules/@tanstack/start-plugin-core/dist/esm/prerender.js:138
            throw new Error(`Failed to fetch ${page.path}: ${res.statusText}`, {
                  ^

Error: Failed to fetch /: Internal Server Error
    at file:///home/codebench/Dev/ts-start-bug/node_modules/.pnpm/@tanstack+start-plugin-core@1.134.12_@tanstack+react-router@1.134.12_react-dom@19.2.0_r_967f5b275724ce77a0f689c31de802f9/node_modules/@tanstack/start-plugin-core/dist/esm/prerender.js:138:19
    at async file:///home/codebench/Dev/ts-start-bug/node_modules/.pnpm/@tanstack+start-plugin-core@1.134.12_@tanstack+react-router@1.134.12_react-dom@19.2.0_r_967f5b275724ce77a0f689c31de802f9/node_modules/@tanstack/start-plugin-core/dist/esm/queue.js:38:17 {
  [cause]: NodeResponse$1 [Response] {}
}

Node.js v22.18.0
 ELIFECYCLE  Command failed with exit code 1.`

---

With ssr external with ['pg']:
codebench@codebench:~/Dev/ts-start-bug/apps/web$ pnpm build

> web@0.0.1 build /home/codebench/Dev/ts-start-bug/apps/web
> vite build

vite v7.2.0 building client environment for production...
✓ 204 modules transformed.
.output/public/assets/index-DtR-hLxC.js    0.66 kB │ gzip:   0.41 kB
.output/public/assets/main-Dh3ZPKv-.js   352.12 kB │ gzip: 111.39 kB
✓ built in 993ms
vite v7.2.0 building ssr environment for production...
✓ 685 modules transformed.
.nitro/vite/services/ssr/assets/start-HYkvq4Ni.js                             0.06 kB
.nitro/vite/services/ssr/assets/_tanstack-start-manifest_v-B07cSHf9.js        0.45 kB
.nitro/vite/services/ssr/assets/index-XYXuMfZ2.js                             1.23 kB
.nitro/vite/services/ssr/assets/bun-sqlite-dialect-B2O0-0JW-C9efU9gy.js       4.57 kB
.nitro/vite/services/ssr/assets/node-sqlite-dialect-5DWxxNaH-B2JIiB1Z.js      4.59 kB
.nitro/vite/services/ssr/assets/index-DP2UTXPC.js                             6.26 kB
.nitro/vite/services/ssr/assets/index-Dv7V5yx9.js                             8.12 kB
.nitro/vite/services/ssr/server.js                                          116.39 kB
.nitro/vite/services/ssr/assets/router-w0xdFAbu.js                        1,653.52 kB
✓ built in 1.86s
[prerender] Prerendering pages...
[prerender] Concurrency: 8
[prerender] Crawling: /
Error [ERR_MODULE_NOT_FOUND]: Cannot find package 'pg' imported from /home/codebench/Dev/ts-start-bug/apps/web/.nitro/vite/services/ssr/assets/router-w0xdFAbu.js
Did you mean to import "pg/lib/index.js"?
    at Object.getPackageJSONURL (node:internal/modules/package_json_reader:255:9)
    ... 7 lines matching cause stack trace ...
    at ModuleJob._link (node:internal/modules/esm/module_job:183:49) {
  cause: Error [ERR_MODULE_NOT_FOUND]: Cannot find package 'pg' imported from /home/codebench/Dev/ts-start-bug/apps/web/.nitro/vite/services/ssr/assets/router-w0xdFAbu.js
  Did you mean to import "pg/lib/index.js"?
      at Object.getPackageJSONURL (node:internal/modules/package_json_reader:255:9)
      at packageResolve (node:internal/modules/esm/resolve:767:81)
      at moduleResolve (node:internal/modules/esm/resolve:853:18)
      at defaultResolve (node:internal/modules/esm/resolve:983:11)
      at ModuleLoader.defaultResolve (node:internal/modules/esm/loader:783:12)
      at #cachedDefaultResolve (node:internal/modules/esm/loader:707:25)
      at ModuleLoader.resolve (node:internal/modules/esm/loader:690:38)
      at ModuleLoader.getModuleJobForImport (node:internal/modules/esm/loader:307:38)
      at ModuleJob._link (node:internal/modules/esm/module_job:183:49) {
    code: 'ERR_MODULE_NOT_FOUND'
  },
  status: 500,
  statusText: undefined,
  headers: undefined,
  data: undefined,
  body: undefined,
  unhandled: true
}
[prerender] Prerendered 0 pages:
[sitemap] Hint: Pages found, but no sitemap host has been set. To enable sitemap generation, set the `sitemap.host` option.

[nitro 11:00:13 am] ◐ Building [Nitro] (preset: node-server, compatibility: 2025-11-06)
file:///home/codebench/Dev/ts-start-bug/node_modules/.pnpm/@tanstack+start-plugin-core@1.134.12_@tanstack+react-router@1.134.12_react-dom@19.2.0_r_967f5b275724ce77a0f689c31de802f9/node_modules/@tanstack/start-plugin-core/dist/esm/prerender.js:138
            throw new Error(`Failed to fetch ${page.path}: ${res.statusText}`, {
                  ^

Error: Failed to fetch /: Internal Server Error
    at file:///home/codebench/Dev/ts-start-bug/node_modules/.pnpm/@tanstack+start-plugin-core@1.134.12_@tanstack+react-router@1.134.12_react-dom@19.2.0_r_967f5b275724ce77a0f689c31de802f9/node_modules/@tanstack/start-plugin-core/dist/esm/prerender.js:138:19
    at async file:///home/codebench/Dev/ts-start-bug/node_modules/.pnpm/@tanstack+start-plugin-core@1.134.12_@tanstack+react-router@1.134.12_react-dom@19.2.0_r_967f5b275724ce77a0f689c31de802f9/node_modules/@tanstack/start-plugin-core/dist/esm/queue.js:38:17 {
  [cause]: NodeResponse$1 [Response] {}
}

Node.js v22.18.0
 ELIFECYCLE  Command failed with exit code 1.

Start with the linked ts-start-bug reproduction and run pnpm build in SPA mode with Nitro, first without and then with ssr: { external: ["pg"] }. Compare the two failure paths and the working non-SPA build; done means the SPA-mode monorepo build and prerender complete successfully without either reported error.