/api/auth/setup returns 401 Unauthorized after deploying (Kinde Next.js SDK)

TL;DR

Fixed upstream in PR #268 (the setup flow handling); upgrade @kinde-oss/kinde-auth-nextjs to a release from February 2025 or later containing that fix. The maintainers confirmed the fix in the thread after discussing the deploy-vs-local difference internally.

Steps

1. Fixed upstream in PR #268 (the setup flow handling); upgrade @kinde-oss/kinde-auth-nextjs to a release from February 2025 or later containing that fix. The maintainers confirmed the fix in the thread after discussing the deploy-vs-local difference internally. If the 401 persists on a current SDK version, double-check that the deployed environment serves the same auth routes as local, since a missing route produces the same symptom.
2. Take the question above and check if it matches what you're seeing. If it does, work through the verified fix step by step. Start with the cause described first, because that's what tells you the fix applies to your setup, then apply the changes in the order given. Verify by re-running whatever failed before, and expect the same behavior the thread author reported.

When to use

You are seeing this: The /api/auth/setup route in @kinde-oss/kinde-auth-nextjs returned 401 Unauthorized after deployment, while everything worked locally. Use this skill when you run into "/api/auth/setup returns 401 Unauthorized after deploying (Kinde Next.js SDK)".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

Someone asked: The /api/auth/setup route in @kinde-oss/kinde-auth-nextjs returned 401 Unauthorized after deployment, while everything worked locally. The setup endpoint rejected the request in the production environment with no useful error beyond the 401. Local dev and production behaved differently, which pointed at the SDK's setup flow rather than the app's configuration. The verified answer: Fixed upstream in PR #268 (the setup flow handling); upgrade @kinde-oss/kinde-auth-nextjs to a release from February 2025 or later containing that fix. The maintainers confirmed the fix in the thread after discussing the deploy-vs-local difference internally. If the 401 persists on a current SDK version, double-check that the deployed environment serves the same auth routes as local, since a missing route produces the same symptom. Source: https://github.com/kinde-oss/kinde-auth-nextjs/issues/170 Discussion and confirmation live at https://vectle.com/threads/thr5qHnip03dtNzvj9H75pIQ