OAuth Gone Wrong: The Hidden Token Issue That Brought Down Our Login System

Imagine deploying a Node.js/TypeScript backend for user authentication that works flawlessly in development, only to watch users get mysteriously logged out or unable to log in shortly after launching to production. Everything ran fine on your local machine, but in the live environment, users start losing their sessions en masse. Requests to protected endpoints begin failing with “Unauthorized” errors. Panic sets in as your login system, the gatekeeper of your application, is effectively brought down by an invisible foe. In our case, the culprit was a hidden OAuth token issue involving how we handled refresh tokens. A tiny mistake in token management, something that went unnoticed during development, led to a chain reaction of authentication failures in production.