Some server-side modules incorrectly bundled into the client?

Which project does this relate to?

Start

Describe the bug

Starting with @tanstack/react-start@1.134.7, I think server-side modules are being incorrectly bundled into the client bundle. For example, in the Clerk SDK, this error shows up in the browser console when running dev server:

Uncaught (in promise) SyntaxError: The requested module '/node_modules/cookie/dist/index.js?v=d2ee33e7' does not provide an export named 'parse' (at chunk-CEKR2FXD.mjs?v=d2ee33e7:4283:10)Understand this error
client:865

Likely related to #5717

Your Example Website or App

https://github.com/clerk/clerk-tanstack-react-start-quickstart/pull/6/files

Steps to Reproduce the Bug or Issue

Clone the repo attached
Switch to the cookie-module-leak branch
Run npm run dev, see browser console

Expected behavior

Properly externalize server-side modules in client builds.

Screenshots or Videos

No response

Platform

Router / Start Version: 1.134.9
OS: [e.g. macOS, Windows, Linux]
Browser: [e.g. Chrome, Safari, Firefox]
Browser Version: [e.g. 91.1]
Bundler: Vite
Bundler Version: [e.g. 7.0.0]

Additional context

No response

I'm getting this error for swr which is a dependency of Clerk.
Uncaught (in promise) SyntaxError: The requested module 'http://localhost:3000/node_modules/use-sync-external-store/shim/index.js?v=f1295605' doesn't provide an export named: 'useSyncExternalStore'

The index.js is for node_modules/swr/dist/index.mjs. Note that this is not imported by tanstack form but only clerk for me.

$ bun why swr
swr@2.3.4
  └─ @clerk/shared@3.31.0 (requires 2.3.4)
     ├─ @clerk/backend@2.19.3 (requires ^3.31.0)
     │  └─ @clerk/tanstack-react-start@0.26.7 (requires ^2.19.3)

If I understand #5726 correctly it only affects tanstacks internal libraries and not others.

I'm getting this error for swr which is a dependency of Clerk. Uncaught (in promise) SyntaxError: The requested module 'http://localhost:3000/node_modules/use-sync-external-store/shim/index.js?v=f1295605' doesn't provide an export named: 'useSyncExternalStore'

The index.js is for node_modules/swr/dist/index.mjs. Note that this is not imported by tanstack form but only clerk for me.

$ bun why swr
swr@2.3.4
└─ @clerk/shared@3.31.0 (requires 2.3.4)
├─ @clerk/backend@2.19.3 (requires ^3.31.0)
│ └─ @clerk/tanstack-react-start@0.26.7 (requires ^2.19.3)
If I understand #5726 correctly it only affects tanstacks internal libraries and not others.

I'm getting this same issue, and its coming from clerk. Did you find a fix?

I'm getting this error for swr which is a dependency of Clerk. Uncaught (in promise) SyntaxError: The requested module 'http://localhost:3000/node_modules/use-sync-external-store/shim/index.js?v=f1295605' doesn't provide an export named: 'useSyncExternalStore'
The index.js is for node_modules/swr/dist/index.mjs. Note that this is not imported by tanstack form but only clerk for me.
$ bun why swr
swr@2.3.4
└─ @clerk/shared@3.31.0 (requires 2.3.4)
├─ @clerk/backend@2.19.3 (requires ^3.31.0)
│ └─ @clerk/tanstack-react-start@0.26.7 (requires ^2.19.3)
If I understand #5726 correctly it only affects tanstacks internal libraries and not others.

I'm getting this same issue, and its coming from clerk. Did you find a fix?

I solved it now by using the same approach with optimizeDeps like the PR I linked.
In my vite.config.ts I added these

optimizeDeps: {
    include: ['@clerk/tanstack-react-start', 'cookie'],
  },

One for the clerk issue with useSyncExternalStore and one for cookie which had an issue with parse import. Hope it works for you ✌️

I'm getting this error for swr which is a dependency of Clerk. Uncaught (in promise) SyntaxError: The requested module 'http://localhost:3000/node_modules/use-sync-external-store/shim/index.js?v=f1295605' doesn't provide an export named: 'useSyncExternalStore'

The index.js is for node_modules/swr/dist/index.mjs. Note that this is not imported by tanstack form but only clerk for me.

$ bun why swr
swr@2.3.4
└─ @clerk/shared@3.31.0 (requires 2.3.4)
├─ @clerk/backend@2.19.3 (requires ^3.31.0)
│ └─ @clerk/tanstack-react-start@0.26.7 (requires ^2.19.3)
If I understand #5726 correctly it only affects tanstacks internal libraries and not others.

to me the fix was to rollback @tanstack/react-start to 1.134.6. Any other combinations of optimizeDeps and what not unfortunately did not work at all.

I can also confirm when using Clerk

I'm getting this error for swr which is a dependency of Clerk. Uncaught (in promise) SyntaxError: The requested module 'http://localhost:3000/node_modules/use-sync-external-store/shim/index.js?v=f1295605' doesn't provide an export named: 'useSyncExternalStore'
The index.js is for node_modules/swr/dist/index.mjs. Note that this is not imported by tanstack form but only clerk for me.
$ bun why swr
swr@2.3.4
└─ @clerk/shared@3.31.0 (requires 2.3.4)
├─ @clerk/backend@2.19.3 (requires ^3.31.0)
│ └─ @clerk/tanstack-react-start@0.26.7 (requires ^2.19.3)
If I understand #5726 correctly it only affects tanstacks internal libraries and not others.

to me the fix was to rollback @tanstack/react-start to 1.134.6. Any other combinations of optimizeDeps and what not unfortunately did not work at all.

I have the same problem trying to use work os with start. Rolling back @tanstack/react-start to 1.134.6 fixed the issue also for me

Can also confirm that rolling back to 1.134.6 solved the issue

I'm getting this error for swr which is a dependency of Clerk. Uncaught (in promise) SyntaxError: The requested module 'http://localhost:3000/node_modules/use-sync-external-store/shim/index.js?v=f1295605' doesn't provide an export named: 'useSyncExternalStore'
The index.js is for node_modules/swr/dist/index.mjs. Note that this is not imported by tanstack form but only clerk for me.
$ bun why swr
swr@2.3.4
└─ @clerk/shared@3.31.0 (requires 2.3.4)
├─ @clerk/backend@2.19.3 (requires ^3.31.0)
│ └─ @clerk/tanstack-react-start@0.26.7 (requires ^2.19.3)
If I understand #5726 correctly it only affects tanstacks internal libraries and not others.

I'm getting this same issue, and its coming from clerk. Did you find a fix?

I solved it now by using the same approach with optimizeDeps like the PR I linked. In my vite.config.ts I added these
optimizeDeps: {
    include: ['@clerk/tanstack-react-start', 'cookie'],
  },
One for the clerk issue with useSyncExternalStore and one for cookie which had an issue with parse import. Hope it works for you ✌️

With pnpm, I also had to add public-hoist-pattern[]=cookie to the .npmrc file.
Tested in 1.134.18

has this been finally solved upstream?

Downgrading hasn't helped in my case, sadly. I've downgraded all the way down to 1.125.0 for Tanstack and 0.26.0 for Clerk. This appears to have happened when I introduced Clerk into Tanstack Start application.

However, after following a bunch of advice for both this and the other thread, I managed to get a bandaid fix working.

For my vite.config.ts file I added:

  resolve: {
    alias: [
      {
        find: "use-sync-external-store/shim/index.js",
        replacement: "react",
      },
      {
        find: "cookie",
        replacement: "cookie-es",
      },
    ],
  },

For my package.json file I added:
"cookie-es": "^2.0.0",

My versions are: (I've tested a lot of different versions and doesn't appear to matter tmk)

  # TanStack
  "@tanstack/react-form": ^1.27.1
  "@tanstack/react-query": ^5.90.12
  "@tanstack/react-query-devtools": ^5.91.1
  "@tanstack/react-router": ^1.140.0
  "@tanstack/react-router-devtools": ^1.140.0
  "@tanstack/react-router-ssr-query": ^1.140.0
  "@tanstack/react-start": ^1.140.0
  "@tanstack/react-table": ^8.21.3

  # Auth
  "@clerk/tanstack-react-start": ^0.27.8

No other code changes needed on my end, and this seems to be the maximum changes needed, remove any of this (at least for me) and it seems to break sadly. Hope this helps someone!

Still an issue and I can confirm that rolling back to 1.134.4 seems to fix things for now.

Can confirm that the issue still exists - the server modules are incorrectly bundled into the client-side using @tanstack/react-start@1.142.5

@nikosdouvlis

@nikosdouvlis please provide a reproducer

Add below to vite.config.ts:
resolve: { alias: [ { find: "use-sync-external-store/shim/index.js", replacement: "react", }, { find: "cookie", replacement: "cookie-es", }, ], },

"@tanstack/react-start": "^1.132.0",
"@clerk/tanstack-react-start": "^0.27.8",

Add below to vite.config.ts: resolve: { alias: [ { find: "use-sync-external-store/shim/index.js", replacement: "react", }, { find: "cookie", replacement: "cookie-es", }, ], },

"@tanstack/react-start": "^1.132.0", "@clerk/tanstack-react-start": "^0.27.8",

You can update @clerk/tanstack-react-start to latest and remove the cookie-es replacement here. The cookie package is now bundled into the @clerk/backend package.

PR updating the starter to have this temporary fix - #6341

@wobsoriano

yeah @wobsoriano I'm still getting this and have for months. It's becoming more of a problem because I have to have my tanstack start versions pinned and can't update. Seemingly a Clerk issue...

Thanks for all the help.

Uncaught (in promise) SyntaxError: The requested module '/@fs/acme/node_modules/.bun/use-sync-external-store@1.6.0+83d5fd7b249dbeef/node_modules/use-sync-external-store/shim/index.js?v=5fc99785' does not provide an export named 'useSyncExternalStore' (at index.mjs?v=5fc99785:2:10)

yeah @wobsoriano I'm still getting this and have for months. It's becoming more of a problem because I have to have my tanstack start versions pinned and can't update. Seemingly a Clerk issue...

Thanks for all the help.
Uncaught (in promise) SyntaxError: The requested module '/@fs/acme/node_modules/.bun/use-sync-external-store@1.6.0+83d5fd7b249dbeef/node_modules/use-sync-external-store/shim/index.js?v=5fc99785' does not provide an export named 'useSyncExternalStore' (at index.mjs?v=5fc99785:2:10)

You can skip pinning versions and add the temporary fix! (ref)

yeah @wobsoriano I'm still getting this and have for months. It's becoming more of a problem because I have to have my tanstack start versions pinned and can't update. Seemingly a Clerk issue...
Thanks for all the help.
Uncaught (in promise) SyntaxError: The requested module '/@fs/acme/node_modules/.bun/use-sync-external-store@1.6.0+83d5fd7b249dbeef/node_modules/use-sync-external-store/shim/index.js?v=5fc99785' does not provide an export named 'useSyncExternalStore' (at index.mjs?v=5fc99785:2:10)
You can skip pinning versions and add the temporary fix! (ref)

the temporary fix being 0.27.14? If so, I still have this same error on that version too

@jjrise

@jjrise the alias here. There's an old, similar issue here.

fwiw, we're removing SWR in favor of TanStack Query and that means this error will be gone as well.

fix(start-plugin-core): remove crawlFrameworkPkgs from optimizeDeps.e…

@wobsoriano

@wobsoriano - has the SWR dependency been finally removed then? Are we safe to update to latest version without any of the patches mentioned above?

@leonfs

@leonfs SWR will be removed in the next Clerk SDKs major release. That's probably next month. For now you still need to patch use-sync-external-store

// vite.config.ts
resolve: { alias: [ { find: "use-sync-external-store/shim/index.js", replacement: "react", } ], }

feat: migrate TanStack Start from Vinxi to Vite 7 + Nitro

Hi all 👋

We released Clerk Core 3, which includes a migration from swr to @tanstack/react-query. This means the error described here is now resolved for Clerk users.

I'm leaving the issue open, as it still applies to developers who are using libraries that depend on use-sync-external-store, like swr.

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Some server-side modules incorrectly bundled into the client? #5738

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Some server-side modules incorrectly bundled into the client? #5738

Description

Which project does this relate to?

Describe the bug

Your Example Website or App

Steps to Reproduce the Bug or Issue

Expected behavior

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mackattack3k commented on Nov 5, 2025

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