Overview

No spike in CPU. Error budgets looked fine at a glance.

Users still reported blank pages in a thin slice of traffic.

Logs only showed upstream resets with no clear application exception.

The culprit was a stale keep-alive timeout between nginx and the app.

Aligning idle timeouts stopped the intermittent 502s within an hour.

We also added a dashboard for upstream reset reasons so the next page is faster.