Stripe Checkout succeeds but Next.js app still shows unpaid: debugging the flow

A developer describes a common problem where a customer completes a Stripe payment yet is sent back to pricing when clicking through from the success page. The author, who builds the Funnel service used in the walkthrough, recommends tracing the purchase through the app, including which user owns it and whether the payment worker has processed it. A key step is matching the app user ID, Funnel customer ID, Checkout ID, and Stripe Session ID, which can expose mismatched accounts or incorrect access lookups. The guide also explains linking the Funnel customer ID to the app user in the database and capturing the customer through a server-side adapter. It notes that verification errors can stem from unverified emails or missing token claims.