Postmortem Attendees

Right people.

Required attendees

The required attendee list is the floor. Without these people, the post-mortem is a ceremony, not an investigation; the action items lack the context to be useful.

• Incident commander. Owned the response; has the timeline; per-incident the IC is non-optional.
• On-call engineers. Ground truth on what happened technically; per-incident the responders bring the in-the-room knowledge.
• Service owners. Per-affected-service the long-term-context owner; supports root-cause depth beyond the immediate trigger.
• PM scribe. Per-PM the explicit scribe; catches the action items in real time so they do not evaporate.

Optional attendees

The optional list grows the post-mortem’s reach without bloating the room. Invite by impact and by who has follow-up to do; not by hierarchy.

• Adjacent teams. Per-affected-team representative; supports cross-team learning without pulling whole teams.
• Product manager. Per-customer-impact PM; product implications of contributing factors land here.
• Engineering leadership. Per-investment-decision leadership presence; resource decisions may follow the PM.
• Vendor account manager. Per-vendor incident the vendor representative; supports cross-vendor learning when the cause is upstream.

Pitfalls

Most post-mortem failures are attendance failures. Either the room is too big to function or too small to capture the truth.

• Mandatory entire-org attendance. 30 people in a room is theatre; nothing gets accomplished; the action items are diluted.
• Skipping the PM because attendance is hard. Async-only loses tone and dynamics; per-major-incident the synchronous PM matters.
• Including too few people. Missing context produces shallow PMs; per-PM the right perspectives, not the minimum.
• No explicit role per attendee. Per-attendee the explicit role going in; supports productive discussion instead of meandering.

Size guidelines

The right size is the smallest room that captures the full picture. Cross-team incidents are the exception; send representatives, not whole teams.

• 5-10 people for SEV1. Per-SEV1 the right room size; enough perspectives, small enough to function.
• 3-5 people for SEV2. Per-SEV2 the smaller PM; smaller scope, tighter group.
• Cross-team incidents. Per-team one or two representatives; not whole teams; the room stays manageable.
• Per-PM facilitation. Per-PM explicit facilitator; supports productive discussion; without one, the room drifts.