How to Fix Clerk Auth Error in AI-Built Apps

Clerk authentication fails with cryptic errors during sign-in, token verification, or middleware. AI-generated Clerk integrations often misconfigure environment variables or middleware order.

Error messages you might see

ClerkJS: Token verification failed. Could not verify session token.
Error: Clerk: auth() was called but Clerk can't detect usage of clerkMiddleware()

Why this happens in AI-generated code

1

Missing or incorrect environment variables

AI code references wrong env variable names or mixes up publishable key and secret key.

2

Middleware not applied to correct routes

ClerkMiddleware is configured but doesn't match the routes that need authentication.

3

Clock skew in token verification

Server time is out of sync, causing JWT tokens to appear expired or not-yet-valid.

How to fix it

1

Verify environment variables

Ensure `NEXT_PUBLIC_CLERK_PUBLISHABLE_KEY` and `CLERK_SECRET_KEY` are set correctly. Never prefix the secret key with NEXT_PUBLIC_.

2

Configure middleware matcher correctly

Export a `config` with a `matcher` array that covers all routes needing auth but excludes public assets and API webhooks.

3

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Frequently asked questions

Why does Clerk work locally but not in production?

Environment variables are often missing in production. Check your hosting platform's env configuration matches your .env.local.

How do I protect API routes with Clerk?

Use `auth()` from `@clerk/nextjs/server` in your API route handler to get the authenticated user's ID.

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