This content originally appeared on DEV Community and was authored by Nuno Tomás
When an outage strikes and your service goes down, the immediate priority is getting things back online. But once the dust settles, there’s another crucial step that many teams overlook or rush through: writing the incident post-mortem.
A well-crafted post-mortem isn’t just a box-ticking exercise—it’s your opportunity to transform a painful downtime experience into valuable insights that prevent future incidents and improve your incident response process.
What Is an Incident Post-Mortem?
An incident post-mortem is a structured review of what happened during an outage or service disruption. It documents the timeline of events, identifies root causes, and outlines action items to prevent similar incidents from recurring.
Think of it as your team’s learning journal—a place to capture lessons without blame and focus on continuous improvement.
Why Post-Mortems Matter for Your Incident Management
Skipping post-mortems might save time in the short term, but it’s a costly mistake. Here’s why they’re essential:
1. They prevent repeat incidents
Without understanding why something broke, you’re likely to face the same problem again. Post-mortems help you identify and fix systemic issues.
2. They improve your MTTR
By documenting what worked and what didn’t during incident response, you can streamline your processes and reduce your Mean Time to Resolution. For more strategies on this, check out our guide on how to reduce MTTR.
3. They build team knowledge
Post-mortems spread expertise across your team. When everyone understands past incidents, they’re better equipped to handle future ones.
4. They demonstrate accountability
Sharing post-mortems with stakeholders and customers shows you take downtime seriously and are committed to improvement.
The Anatomy of an Effective Post-Mortem
A good post-mortem follows a consistent structure that makes it easy to write and read. Here’s what to include:
1. Incident Summary
Start with a brief overview that answers:
- What happened?
- When did it happen?
- How long did it last?
- Who was affected?
- What was the business impact?
Keep this section concise—aim for 3-4 sentences that give readers the essential context.
2. Timeline of Events
Document the incident chronologically, including:
- When the issue was first detected
- Key actions taken during the response
- When service was restored
- When the incident was officially closed
Be specific with timestamps and include who did what. This timeline is invaluable for identifying response delays and communication gaps.
3. Root Cause Analysis
This is the heart of your post-mortem. Dig deep to understand not just what broke, but why. Use techniques like:
- The “5 Whys” method
- Fishbone diagrams
- Fault tree analysis
Remember: there’s often more than one contributing factor. Document all of them.
4. What Went Well
Post-mortems shouldn’t be all doom and gloom. Highlight what worked:
- Quick detection methods
- Effective incident communication
- Team members who went above and beyond
- Tools that performed as expected
Celebrating successes reinforces good practices and boosts team morale.
5. What Could Be Improved
Be honest about what didn’t work:
- Delayed detection or response
- Communication breakdowns
- Missing documentation
- Inadequate monitoring
Frame these as opportunities for improvement, not failures.
6. Action Items
Translate your findings into concrete next steps:
- Assign each action to a specific person
- Set realistic deadlines
- Prioritize based on impact and effort
- Include both immediate fixes and long-term improvements
Without clear action items, your post-mortem is just an interesting story.
Best Practices for Writing Post-Mortems
Keep It Blameless
Focus on systems and processes, not people. Instead of “John forgot to check the logs,” write “The log checking process wasn’t clearly documented.”
Write While It’s Fresh
Schedule your post-mortem within 48 hours of the incident. Memories fade quickly, and you’ll lose important details if you wait.
Involve the Right People
Include everyone who played a role in the incident response, plus key stakeholders who can approve and implement improvements.
Use Plain Language
Avoid technical jargon where possible. Your post-mortem might be read by non-technical stakeholders who need to understand what happened.
Be Specific
Vague statements like “improve monitoring” aren’t helpful. Instead, write “Add CPU utilization alerts with thresholds at 80% and 90%.”
Share Appropriately
Decide who needs to see the full post-mortem versus a summary. Consider sharing key findings with customers to build trust—for tips on this, see our guide on incident communication best practices.
Common Post-Mortem Pitfalls to Avoid
1. Making it too long
Aim for clarity, not comprehensiveness. A concise post-mortem that gets read is better than a detailed one that doesn’t.
2. Focusing only on technical details
Include process and communication issues too. Often, these are bigger contributors to extended downtime than technical failures.
3. Skipping follow-up
Schedule regular reviews to ensure action items are completed. Otherwise, your post-mortems become wish lists.
4. Not sharing lessons learned
Post-mortems are most valuable when their insights spread across your organization. Create a searchable repository of past incidents.
Making Post-Mortems Part of Your Culture
The best teams treat post-mortems as learning opportunities, not punishment. Here’s how to build this culture:
- Make them routine for all significant incidents
- Celebrate teams that write thorough post-mortems
- Share interesting findings in team meetings
- Track metrics on action item completion
- Review old post-mortems to measure improvement
Tools like StatusRay can help by automatically capturing incident timelines and communication logs, making it easier to write comprehensive post-mortems without relying solely on memory.
Conclusion
Effective post-mortems are the difference between teams that repeatedly fight the same fires and those that continuously improve their reliability. By following a structured approach, maintaining a blameless culture, and focusing on actionable outcomes, you can transform every outage into an opportunity for growth.
Remember: the goal isn’t to document failure—it’s to build a more resilient system and a stronger team. Start with your next incident, and make post-mortems a cornerstone of your incident management strategy.
Frequently Asked Questions
How soon after an incident should we conduct a post-mortem?
Ideally, schedule your post-mortem within 24-48 hours after the incident is resolved. This ensures details are still fresh in everyone’s minds while allowing enough time for immediate recovery tasks. For major incidents, you might hold a quick debrief immediately and a more thorough review within a week.
Who should participate in the post-mortem meeting?
Include everyone directly involved in detecting, responding to, or resolving the incident. Also invite key stakeholders who can approve resources for improvements and team members who might face similar issues. Limit attendance to 6-8 people for productive discussion—others can review the written document later.
How long should a post-mortem document be?
Aim for 2-4 pages for most incidents. The document should be comprehensive enough to understand what happened and what you’ll do differently, but concise enough that people will actually read it. Complex incidents might require more detail, but consider creating both a detailed version and an executive summary.
Should we share post-mortems with customers?
For significant outages affecting customers, sharing a simplified version of your post-mortem can build trust and demonstrate accountability. Focus on what happened, how you’re preventing recurrence, and skip internal technical details. Always review with legal and leadership before external sharing.
What’s the difference between a post-mortem and a retrospective?
Post-mortems focus specifically on incidents and outages, analyzing what went wrong and how to prevent similar issues. Retrospectives are broader team reviews that happen regularly (like after sprints) to improve general processes. Post-mortems are reactive to problems, while retrospectives are proactive improvement exercises.
How do we ensure action items from post-mortems actually get completed?
Assign each action item to a specific owner with a clear deadline. Add these items to your team’s regular work tracking system, not a separate document. Schedule monthly reviews to check progress, and include completion rates in team metrics. Consider making action item completion part of performance reviews to emphasize their importance.
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This content originally appeared on DEV Community and was authored by Nuno Tomás