What is a blameless postmortem?

Why blameless?

If people are punished for mistakes, they hide them, and the organisation loses the information it needs to improve. Assuming that people acted sensibly with what they knew at the time moves the question from “who” to “what made this easy to do”.

What goes in a postmortem?

• A short summary and the impact on users.
• A timeline of events, with times.
• The causes and contributing factors.
• What went well and what was lucky.
• Action items, each with an owner and a due date.

How do you run the meeting?

Share the draft timeline beforehand, ask open questions such as “what did you see at that point?”, and keep the focus on conditions and decisions rather than individuals. Someone should keep the conversation off blame when it drifts.

What makes a good action item?

It is specific, has one owner and a date, and changes the system, for example adding an alert, a guard or an automated check. “Be more careful” is not an action item, because it relies on memory.

Does blameless mean no accountability?

No. People are still accountable for acting in good faith and for following up on actions. What changes is that the review explains the failure instead of assigning fault. See also SLIs, SLOs and error budgets.

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