We’ve tracked down the issue yesterday and the team is working on a fix 🙏

The team is taking a look as we speak. It should be resolved in a few days.

Our apologies for the inconvenience.

You can test the fix by following these steps:

• Include the following environment variable in your deployment (through the environment variables UI): Key: FORCE_BUILDER_TAG. Value: canary

• If you have a vercel.json file, then you can follow the same method:

{
  "build": {
    "env": {
      "FORCE_BUILDER_TAG": "canary"
    }
  }
}

Let us know if you have any positive results.

Hello everyone 👋 A fix has been shipped to canary (@vercel/next@canary). I will post updates on how to try it out here.

@timneutkens I’ve contacted support already, but you can reproduce it here:

• https://github.com/belgattitude/vercel-monorepo-test
• https://vercel-monorepo-test-web-app.vercel.app/

@vongohren Thank you for the comment! You gave me a hint that I maybe have the same issue. Comparing with your file I found out that line config.devtool = 'eval-source-map'; is causing this error on Vercel in my case.

Removing it or adding conditional dev/build check helped for me.

Even though I resolved my issue, I haven’t found any docs about it and in my custom server project I haven’t had the issue with source-map enabled.

I find it handy on dev servers to be able to inspect scripts. Is this bug? Or designed behaviour? Where can I read the info about webpack settings that should be blocked on serverless vercel deploy?

Hey @paulogdm I can confirm it fixes the issue with api-route: https://github.com/belgattitude/vercel-monorepo-test/pull/10.

Great work !

PS: any idea why a simple api is so slow ?:

• link: https://vercel-monorepo-test-web-app-git-vercelforcebuildertag.belgattitude.vercel.app/api/hello (200/300ms)
• source: https://github.com/belgattitude/vercel-monorepo-test/blob/master/apps/web-app/src/pages/api/hello.ts