The Bug That Made Me Question Reality for a Few Hours

Everything worked. Which, in hindsight, was the problem. I had just shipped a small backend change....

Everything worked.
Which, in hindsight, was the problem.

I had just shipped a small backend change. The kind you barely think about. Tests passed. Local setup was green. I even did that extra manual check we all pretend to always do.

A few hours later, production started acting… weird.

Not broken. Not down. Just off.
Some requests failed. Others succeeded. Refresh the page and the result changed. At one point I honestly wondered if I was accidentally load testing my own sanity.

My first thought was data. Then traffic. Then timing. Then maybe I had angered the JavaScript gods.

I added logs. Lots of logs. The kind you swear you’ll remove later.

Nothing obvious showed up.

That’s when I noticed something small and extremely annoying. One configuration value was undefined in production but perfectly fine on my machine.

I stared at it longer than I’d like to admit.

I had assumed my environment variables were the same everywhere. They weren’t. Locally, I had an old config file quietly saving me. In production, that variable simply did not exist, and my code reacted to that fact with chaos.

Once I knew that, the fix was almost boring. Add validation. Set a default. Deploy again.

The real bug wasn’t the code. It was my assumption that environments behave politely and consistently.

Since then, whenever a bug feels random, I start by asking a simple question: what am I assuming is “obviously the same” when it probably isn’t?

It saves time. And a small amount of dignity.