A post on Indie Hackers this week described something that should scare every founder who built their SaaS with an AI coding tool in the last year.
The pattern: a Stripe webhook handler catches invoice.payment_failed. It returns 200 OK. Stripe marks it as delivered and moves on. But inside the handler, nothing actually happens. No database updated. No access revoked. The user keeps full access to the product ā forever.
The founder doesn't notice because their Stripe dashboard shows MRR coming in from other customers. Everything looks fine. The leak only shows up at the intersection of two systems: who failed to pay in Stripe, and who still has active access in the database. Neither system flags the overlap automatically.
This is the most common hidden bug in AI-generated SaaS right now. Tools like Cursor and Lovable are excellent at building the happy path. Checkout works, user gets access, everything looks good. The failure paths ā payment fails, subscription cancels, refund issued ā are the parts AI tools generate poorly because the tutorials they learned from skip them.
The detection problem
The reason this bug is so hard to catch isn't technical ā it's visibility. If you're not actively comparing your failed payment events in Stripe against your active users in your database, the bug is invisible.
Most founders check their Stripe dashboard periodically. They see total MRR, recent charges, maybe a graph. They don't see the intersection of failed payments and active access because Stripe doesn't surface that view by default.
What helps
When I built Autoreport ā a tool that sends Stripe founders a weekly PDF every Monday morning ā one of the deliberate design choices was to put failed payments, refunds, and disputes in the same report as active customer data. Not because I anticipated this specific bug, but because I wanted founders to see their Stripe week as a complete picture, not just the positive signals.
A weekly report won't replace a proper webhook audit. But it creates a forcing function: every Monday, you see your failed payments side by side with your revenue. If those numbers don't add up over time, something is wrong.
What to check right now
If you built your SaaS with an AI tool, open your webhook handler and find the case for invoice.payment_failed. Look at what's actually inside it. If it logs and returns without touching your database or your user's access state, you have this bug.
The fix is straightforward once you find it. The hard part is knowing to look.
If you want a weekly view of your Stripe data without building a dashboard, Autoreport sends you a PDF every Monday morning.
