Supabase authentication and session handling issues in v0 preview deployments

v0
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Auth works in production but not in v0 preview (beta).
Supabase login succeeds in production deployments, but in v0 beta preview the user isn’t redirected to protected routes after login. Same code, no auth changes.

Is auth/session handling fully supported in v0 preview, or are there known limitations with middleware/cookies?

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Hi @bilalalam58-7827, thanks for reaching out. I’m the community’s system bot.

Sorry to hear you’re experiencing this auth issue with v0 preview deployments. This is definitely frustrating when everything works fine in production but breaks in the preview environment.

Auth and session handling should generally work in v0 preview deployments, but there are some common differences that can cause issues like the one you’re describing.

Common Causes

The most likely culprits are environment-related differences:

  • Environment variables - Preview deployments might be missing auth-related env vars or using different values
  • Redirect URLs - Supabase auth callbacks might not be configured for your preview domain
  • Cookie settings - Different domains can affect cookie behavior, especially with secure and sameSite settings
  • Middleware execution - Preview environments sometimes handle middleware differently

Quick Debugging Steps

Check your preview deployment’s environment variables first:

# Ensure these are set in your preview environment
SUPABASE_URL=your-url
SUPABASE_ANON_KEY=your-key
NEXTAUTH_URL=your-preview-domain

Also verify your Supabase project settings include your preview domain in the allowed redirect URLs.

Getting More Help

Could you share your v0 chat link? It will look something like https://v0.dev/chat/... - this will help me see the specific implementation and identify what might be causing the redirect issue.

You can also check your preview deployment’s function logs in the Vercel dashboard to see if there are any auth-related errors during the login flow.

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i already have these keys but still my login system is not working in preview even this is duplicate branch from old working branch

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CleanShot 2026-02-06 at 17.46.37@2x
CleanShot 2026-02-06 at 17.46.37@2x1386×536 43 KB

Can you make sure that you’ve selected all these environments?

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I have a similar but different issue. The home page loads, but when I clicked the google login button, the page will be blocked with these console errors:

Framing ‘https://xxxxxx.supabase.co/’ violates the following Content Security Policy directive: “frame-src ‘self’ http://localhost:* https://.vusercontent.net/ https://.lite.vusercontent.net/ https://generated.vusercontent.net/ https://.vercel.run/ https://.vercel.app/ https://*.vercel.sh/ https://vercel.live/ https://vercel.com https://vercel.fides-cdn.ethyca.com/ https://js.stripe.com/”. The request has been blocked.

How can I add the supabase / google login redirection url into the allowed domains for CSP?

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yes was selected

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I’ve identified the root cause of the “auth not working” reports in v0 beta previews. Authentication succeeds, but navigation/redirect after login does not occur in the beta environment. Users must manually navigate via the route bar (e.g. /dashboard) to access the app.

Because post-login navigation is suppressed in beta, it appears like an infinite login or NEXT_REDIRECT issue even though the session is valid. Production deployments redirect normally this is specific to the beta preview.

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Thanks for sharing what worked for you! Hopefully this helps others in the community.

I’ll get this in front of our team to review!

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