Troubleshooting: Google OAuth

Symptoms

• After Google consent, user is redirected to login/error instead of dashboard.
• Browser shows Authentication failed or Invalid token received.
• Backend callback route appears to run, but frontend never gets valid session.
• Google OAuth screen shows redirect_uri_mismatch.

Common causes

• Google OAuth redirect URI does not exactly match backend callback URL.
• Backend GOOGLE_CALLBACK_URL is outdated or uses an old domain.
• Frontend/backend URLs changed (new Koyeb or Vercel domain) but OAuth config was not updated.
• Frontend env (VITE_GOOGLE_AUTH_URL) points to the wrong backend domain.
• CORS/routing issues prevent auth callback flow from completing.

Diagnostic steps

1. Verify backend callback URL works:
   • https://api.korta.click/api/v1/auth/google/callback
2. Check Google Cloud OAuth client config:
   • Authorized JavaScript origins includes:
     • https://korta.click/
   • Authorized redirect URIs includes:
     • https://api.korta.click/api/v1/auth/google/callback
3. Check backend env vars:
   • GOOGLE_CLIENT_ID
   • GOOGLE_CLIENT_SECRET
   • GOOGLE_CALLBACK_URL=https://api.korta.click/api/v1/auth/google/callback
   • FRONTEND_URL=https://korta.click/
4. Check frontend env:
   • VITE_GOOGLE_AUTH_URL=https://api.korta.click/api/v1/auth/google
5. Redeploy both services after env/config changes.

Fixes

• Make all OAuth URLs exact and consistent across:
  • Google Console
  • Backend env
  • Frontend env
• Remove stale domains from callback/origin settings.
• Ensure backend service is mounted at public path / on Koyeb.
• Ensure production frontend uses the same domain configured in Google origins.

Verification

• Clicking “Continue with Google” opens Google consent correctly.
• After consent, user is redirected to frontend callback route and then dashboard.
• Frontend stores accessToken and authenticated routes load.
• GET /api/v1/auth/me succeeds with Bearer token after OAuth login.