← 문제 라이브러리
Network Beginner 14 min

502 Bad Gateway: Nginx cannot connect to its upstream after an app upgrade

Read Nginx's upstream error to find why the proxy cannot reach the app.

무료
시나리오

Right after upgrading a Node.js app, every request through Nginx returns 502 while the app process is running.

먼저 볼 것
  • Understand the main investigation order for Network incidents.
  • Separate user-facing symptoms from the deeper technical cause.
  • Describe both quick recovery actions and follow-up improvements.
점검 체크리스트
  1. Summarize the symptom and the current impact first.
  2. Check recent changes before collecting deeper diagnostics.
  3. Verify config, runtime state, and recovery path in order.
복구와 재발 방지

Write down the minimal recovery path first, then capture the improvements that reduce repeat incidents.

같이 보면 좋은 질문
Should I translate commands, logs, or product names?

No. Keep commands, logs, file names, APIs, and product names unchanged, then explain the reasoning in the selected UI language.

What should the answer focus on?

State the root cause, the evidence that supports it, and the safest recovery direction.

Why can the scenario remain in the original language?

The source scenario is treated as an incident artifact. Guidance, checklist, hints, and explanations can be localized around it.