On-callHardoc-p014

Subject Postmortem judgmentLevel Senior–Staff~20 minCommon in Reliability & on-call interviewsIndustries Technology

Question

A migration that ran an hour ago wrote incorrect values into a column for a subset of rows, and the app has served wrong data since. How do you handle it?

What a strong answer looks like

Stop the bleeding first (mitigate), then form hypotheses from real signals. Separate root cause from symptom, communicate status as you go, and close with what prevents a repeat.

Learn the concepts

Diagram & narrate the incident

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Run or narrate your approach, then ask the coach.