Post-Mortem

Purpose

A Post-Mortem examines a completed project or incident to extract lessons. The goal is blameless learning: understand systemic causes, celebrate what worked, and create actionable improvements so the organisation does not repeat mistakes.

At a glance

How to run

1. Set the tone (5 min): Emphasise blamelessness. Review the timeline of events factually.
2. What went well (8 min): Silent brainstorm on sticky notes, then share and cluster.
3. What went wrong (10 min): Same format. Encourage root causes, not symptoms.
4. Contributing factors (8 min): For each major issue, ask "Why?" up to five times (5 Whys).
5. Lessons and actions (10 min): Convert insights into specific, owned action items with deadlines.
6. Close (4 min): Summarise top 3 lessons. Agree on how to share findings with the wider organisation.

Materials needed

• Timeline of events (prepared in advance)
• Sticky notes and markers
• Whiteboard or digital board
• Action-item tracker

Pitfalls & common mistakes

• Blame culture: If people feel attacked, they withhold information. Enforce blamelessness explicitly.
• Too soon or too late: Run within 1–2 weeks of the event while memory is fresh.
• No actions: A post-mortem without follow-through is theatre. Assign owners and review.
• Scope explosion: Keep it to one project or incident per session.

Inclusion & accessibility

• Share the timeline in advance so participants can prepare.
• Use silent writing before discussion to include quieter voices.
• Record the session (with consent) for those who cannot attend.
• Provide a written summary afterward.

Variations

• Incident Post-Mortem (SRE style): Focuses on technical root cause, detection time, and remediation.
• Appreciative Post-Mortem: Starts with successes and builds on strengths.
• Timeline Walk: Physically walk along a timeline taped to the wall, adding notes at each phase.

When NOT to use this

• During an ongoing crisis — stabilise first, debrief later.
• When the team is emotionally raw — allow a cooling-off period.
• For trivial events that do not warrant a 45-minute session.

Source & further reading

• Etsy, "Blameless PostMortems and a Just Culture" (Code as Craft blog)
• US Army After Action Review (AAR) framework
• Norman Kerth, *Project Retrospectives* (2001)