Canonical URL: https://medium.com/workspai/your-code-was-fine-your-debugging-order-was-wrong-d02420c38870

TL;DR

If your FastAPI endpoint returns 500 and the code looks fine:

Don’t touch the code first

Check env, dependencies, wiring, and contracts

Most failures are state issues, not logic

This checklist saves hours.

The Night It Happened

Everything looked correct.

The endpoint still returned 500.

I spent 5 hours changing code…

The bug had nothing to do with the code.

What Actually Broke

The issue wasn’t logic.

It was setup drift .

Something in the system state had changed:

environment config

dependency availability

runtime wiring

Code edits only delayed the real fix.

That’s when I changed how I debug.

The 10-Minute Triage Checklist

Before touching any code, I now run this:

1) Environment Integrity (2 min)

Required env vars exist

Values match the active environment

No stale .env file shadowing config

2) Dependency Health (2 min)

DB / Redis / broker reachable

Auth tokens & secrets…