Better AuthBA
Better Auth•6mo ago
Kinshuk

I’m having trouble getting Google OAuth to work with better-auth in my monorepo (Turborepo) setup

Here’s what’s happening:

  • Email/password login works fine (session cookie is set, user is authenticated).
  • Google login fails after redirecting back from Google.
  • The backend logs show: 
    ERROR [Better Auth]: State not found undefined
  • My frontend is on 
    localhost:3000
    , backend is on localhost:5050.
  • The Google Cloud Console redirect URI is set to http://localhost:3000/api/auth/callback/google.
  • The backend redirectURI is also set to http://localhost:3000/api/auth/callback/google.
  • The frontend uses authClient.signIn.social({ provider: "google", callbackURL: "http://localhost:3000/infrahub", disableRedirect: true }) and then manually redirects to the returned URL.
What I’ve tried:
  • Aligning all ports and domains (tried both 3000 and 5050).
  • Clearing cookies and restarting everything.
  • Setting cookie options in the backend to { domain: undefined, sameSite: "lax", secure: false } for local dev.
  • Ensuring the login flow starts and ends on the same port.
Still, I get the "State not found" error after Google redirects back.

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My questions:
  1. What is the correct way to handle the OAuth "state" in a monorepo with separate frontend/backend ports?
  2. Is there a recommended way to proxy or align ports for local development with better-auth?
  3. Are there any special settings needed for cookies or CORS to ensure the state is preserved?
  4. Is it okay to use disableRedirect: true and manually redirect, or does that affect the state/cookie handling?
Any advice or working local dev setups would be greatly appreciated!
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