Google login callback not working after deploy

This usually comes down to redirect URI / OAuth config mismatch between local and production.

Quick checklist

1) Verify the Google OAuth redirect URI in Google Cloud Console

In APIs & Services → Credentials → OAuth 2.0 Client IDs, make sure your Authorized redirect URI exactly matches your deployed callback URL, for example:

• https://yourdomain.com/api/auth/callback/google
• https://your-app.vercel.app/api/auth/callback/google

It must match exactly:

• http vs https
• domain
• path
• trailing slash
• subdomain

2) Check your app’s redirect_uri / callback route

Make sure your app is generating the production callback URL correctly. If you’re using:

• NextAuth / Auth.js: confirm NEXTAUTH_URL or AUTH_URL
• Passport / custom OAuth: confirm the callback URL passed to Google is the production one

3) Set production env vars

Common issue: local env vars still point to localhost.

Examples:

• GOOGLE_CLIENT_ID
• GOOGLE_CLIENT_SECRET
• NEXTAUTH_URL=https://yourdomain.com
• NEXTAUTH_SECRET=...

If using Auth.js v5, also check:

• AUTH_URL
• AUTH_TRUST_HOST=true (sometimes needed behind proxies/platforms)

4) Make sure your deploy platform forwards HTTPS correctly

If you’re behind a proxy/load balancer, your app may think it’s on http:// and generate the wrong callback URL.

5) Check Google Cloud Console “Authorized JavaScript origins”

If your flow needs it, add:

• https://yourdomain.com

6) Inspect the exact error

Common Google errors:

• redirect_uri_mismatch → callback URL mismatch
• unauthorized_client → wrong client type or config
• origin_mismatch → missing JS origin
• access_denied → user denied consent or app verification issues

If you’re using NextAuth/Auth.js

Production issues are often fixed by:

NEXTAUTH_URL=https://yourdomain.com
GOOGLE_CLIENT_ID=...
GOOGLE_CLIENT_SECRET=...

And in Google Console:

https://yourdomain.com/api/auth/callback/google

If you want, send me:

1. The exact error message from Google
2. Your callback URL route
3. Whether you’re using NextAuth/Auth.js, Passport, or custom OAuth
4. Your deploy platform (Vercel, Render, AWS, etc.)

…and I can tell you the exact fix.