Vercel deployment fails with Google Analytics from @next/third-parties showing type error while localhost works fine

Other Questions Google Analytics
1

I’m working on a Next.js application and integrated Google Analytics using the @next/third-parties/google package. Everything runs perfectly when I test it locally in development mode.

However, when I try to deploy my project to Vercel, the build process fails with this TypeScript error:

./app/layout.tsx:28:18
Type error: Type 'string | undefined' is not assignable to type 'string'.
Type 'undefined' is not assignable to type 'string'.

</AuthProvider>
</body>
<GoogleAnalytics analyticsId={process.env.NEXT_PUBLIC_GA_ID} />
                 ^
</html>

The error points to my environment variable NEXT_PUBLIC_GA_ID which seems to be undefined during the Vercel build process. I’ve double checked my environment variables in the Vercel dashboard and they appear to be set correctly.

Why does this work locally but not on Vercel? How can I fix this type error during deployment?

2

same thing happened 2 me last week. vercel’s env vars can be flaky during builds. add a fallback like analyticsId={process.env.NEXT_PUBLIC_GA_ID || ''} or wrap it in a conditional. double-check your env var actually deployed - sometimes takes a few mins to kick in.

3

Had this exact issue on multiple projects. TypeScript gets stricter during Vercel builds vs dev mode.

I don’t just add fallbacks anymore - I validate all environment variables through automation now. Set up a workflow that checks all required env vars exist before deployment and creates proper type definitions.

For a quick fix:

const gaId = process.env.NEXT_PUBLIC_GA_ID;
if (gaId) {
  return <GoogleAnalytics analyticsId={gaId} />;
}
}

But managing env vars manually across environments gets messy fast. I automate everything now - validation, deployment, monitoring. Kills these type errors completely and keeps configs synced.

Check out https://latenode.com for a better approach.

4

Been dealing with this exact scenario for years. Vercel’s build environment handles TypeScript more strictly than your local dev setup.

I usually create a simple wrapper component that handles the undefined case:

function Analytics() {
  const gaId = process.env.NEXT_PUBLIC_GA_ID;
  
  if (!gaId) {
    console.warn('GA_ID not found');
    return null;
  }
  
  return <GoogleAnalytics analyticsId={gaId} />;
}

Then just use <Analytics /> in your layout instead.

Check if you accidentally created the env var in preview/development instead of production in Vercel’s dashboard. I’ve done that more times than I care to admit.

One more thing - redeploy after setting the env vars. Vercel sometimes needs a fresh build to pick them up.