Developer's webhook silently failed on his own app's first real payment due to a truncated secret

A solo developer launched ApiPulse, an API uptime monitoring tool he built over four months, and immediately tested it by paying €5 with his own card. Despite the payment going through and being confirmed by the payment provider, his app failed to upgrade his plan because the webhook endpoint was returning a 401 error. After investigating common causes, he traced the issue to a webhook secret that had been accidentally truncated during a copy-paste into his hosting environment variables. Once corrected, the provider's automatic retry succeeded and the plan activated normally. The incident prompted him to highlight two lessons: always test the full payment chain with real money before launch, and check configuration before assuming the code is at fault.