What is an Incident Postmortem? Writing Guide and Examples

In the dynamic world of technology and business operations, incidents are an inevitable reality. Whether it’s a software glitch, a network outage, or a security breach, incidents can disrupt workflows, impact customer experiences, and even harm a company’s reputation.

However, incidents are not just problems to be solved; they are opportunities for growth, learning, and improvement. That’s where incident postmortems come into play.

What is an Incident Postmortem?

An incident postmortem is a structured analysis and documentation process that takes place after a significant incident or outage. Its primary goal is to identify the root causes of the incident, analyze the events leading up to it, and provide actionable insights to prevent similar incidents in the future.

Postmortems foster a culture of transparency, accountability, and continuous improvement within an organization. They enable teams to learn from mistakes, refine processes, and optimize systems for enhanced reliability and performance.

Key Components of an Incident Postmortem

  1. Summary: Begin with a concise overview of the incident, detailing the impact it had on operations, customers, and stakeholders.

  2. Timeline: Create a chronological sequence of events leading up to and during the incident. This helps pinpoint critical junctures and potential triggers.

  3. Root Cause Analysis: Uncover the underlying factors that contributed to the incident. Was it a software bug, a misconfigured system, or a communication breakdown? Identifying the root cause is essential for implementing effective solutions.

  4. Impact Assessment: Assess the immediate and long-term consequences of the incident. Did it result in financial losses, data breaches, or customer dissatisfaction? Quantify the impact to prioritize improvements.

  5. Contributing Factors: Identify secondary factors that may have exacerbated the incident. This could include issues like lack of redundancy, inadequate monitoring, or insufficient training.

  6. Recommendations: Propose actionable recommendations to prevent similar incidents. These could involve process enhancements, technical fixes, or improved communication protocols.

How to Write an Effective Incident Postmortem

  1. Gather a Cross-Functional Team: Form a diverse team comprising members from different departments involved in the incident. This ensures a comprehensive analysis from various perspectives.

  2. Collect Data: Compile relevant data, logs, and communication records related to the incident. This provides factual context for the postmortem.

  3. Define Objectives: Clearly outline the goals of the postmortem. What do you hope to achieve? Is it preventing future incidents, improving communication, or enhancing system resilience?

  4. Maintain a Neutral Tone: Focus on facts rather than assigning blame. The goal is to learn and improve, not to point fingers.

  5. Use a Structured Format: Organize the postmortem into the key components mentioned earlier: summary, timeline, root cause analysis, impact assessment, contributing factors, and recommendations.

  6. Include Visuals: Graphs, charts, and diagrams can visually represent complex timelines and data, making it easier for readers to grasp the sequence of events.

  7. Share Lessons Learned: Highlight the key takeaways from the incident and discuss how they will inform future decisions and actions.

Incident Postmortem Example

Postmortem: Service Outage Incident

Issue Summary: Duration: August 10, 2023, 14:30 – August 11, 2023, 09:15

Impact: Cloud Storage Service (CSS) at lyonec.com experienced an outage resulting in slow access and intermittent failures for 35% of users.

Root Cause: A database connection pool exhaustion due to a misconfigured connection limit.


  • August 10, 2023, 14:30: Issue detected as monitoring alerts indicated increased latency and error rates.
  • August 10, 2023, 14:45: Engineers initiated investigation, suspecting network congestion.
  • August 10, 2023, 15:30: Network configurations were examined and load balancers were rebooted, but no improvement was observed.
  • August 10, 2023, 16:15: Investigation pivoted to database layer due to lingering suspicions.
  • August 10, 2023, 18:00: Database logs analyzed, revealing a connection pool issue.
  • August 10, 2023, 20:30: Incorrect assumptions led to scaling up instances, exacerbating the issue.
  • August 10, 2023, 22:45: Incident escalated to database administration team.
  • August 11, 2023, 05:30: After intensive debugging, root cause identified: connection pool exhaustion.
  • August 11, 2023, 07:00: Database connection pool settings were optimized to increase connection limit.
  • August 11, 2023, 09:15: Service fully restored as users reported normal access.

Root Cause and Resolution: The root cause of the outage was the exhaustion of the database connection pool. The misconfiguration of the connection limit led to premature depletion of available connections, causing subsequent requests to be queued, leading to slow access and failures.

To resolve the issue, the database connection pool settings were adjusted to allow for a higher connection limit. Additionally, a comprehensive review of connection pool configurations was conducted to ensure optimal settings align with service requirements. This adjustment enabled the service to handle higher connection demands without queuing and latency.

Corrective and Preventative Measures:

  • Immediate Actions:

    • Patch Connection Pool Settings: Adjust connection pool settings to accommodate projected user load and prevent premature depletion.
    • Monitoring Enhancement: Implement real-time monitoring for database connection pool metrics to detect and address potential bottlenecks promptly.
  • Short-Term:

    • Automated Scaling: Develop an automated scaling mechanism to dynamically adjust connection pool limits based on traffic patterns.
    • Thorough Testing: Establish comprehensive load testing scenarios to simulate various user scenarios and ensure connection pool resilience.
  • Long-Term:

    • Redundancy Strategies: Explore implementing multi-region database redundancy to distribute connection load and increase fault tolerance.
    • Incident Response Training: Conduct incident response training for engineers to streamline detection, investigation, and resolution processes.

By implementing these measures, we aim to enhance the stability and reliability of the Cloud Storage Service, ensuring that future incidents are minimized and addressed promptly.

Incident Postmortem Example 2

Now, we can make the post-mortem we just wrote above attractive by adding humour, a pretty diagram or anything that would catch your audience attention.

Let’s go!

Duration: August 10, 2023, 14:30 – August 11, 2023, 09:15

Impact: Remember that feeling when you’re stuck behind a slow-moving snail on the highway? Well, that’s how our Cloud Storage Service (CSS) at lyonec.com felt for 35% of users during this delightful outage. Access was slower than a sloth on a Monday morning.

Root Cause: Picture this: a connection pool party where everyone tried to fit into the same pool. Misconfigured connection limits turned our pool party into a pool puddle, causing the whole system to hiccup.


  • August 10, 2023, 14:30: Our monitoring system lit up like a Christmas tree – not the festive vibe we were hoping for!
  • August 10, 2023, 14:45: Engineers put on their detective hats and chased network gremlins down various rabbit holes.
  • August 10, 2023, 15:30: Load balancers got a reboot, but it seems they were more interested in a siesta than getting back to work.
  • August 10, 2023, 16:15: Our suspicions shifted to the database layer. Turns out, databases can be a bit moody sometimes.
  • August 10, 2023, 18:00: After sifting through logs, we realized the real party was happening in the database connection pool.
  • August 10, 2023, 20:30: In a classic “go big or go home” move, we scaled up instances. The system responded by giving us a virtual eye-roll.
  • August 10, 2023, 22:45: We finally surrendered and sent out a distress signal to the database administration team.
  • August 11, 2023, 05:30: After many sleepless cups of coffee, we unearthed the real culprit: the connection pool was more drained than our coffee mugs.
  • August 11, 2023, 07:00: We gave the connection pool a power-up, allowing it to accommodate more partygoers.
  • August 11, 2023, 09:15: The CSS was back in business, and users celebrated with a virtual high-five.

Root Cause and Resolution:

The connection pool, once the life of the party, had too few spots for guests. We revamped its settings, giving it a makeover worthy of a Hollywood star. With the new settings, our connection pool went from being an introvert to a social butterfly, allowing more connections without causing a traffic jam.

Corrective and Preventative Measures:

  • Immediate Actions:

    • Poolside Maintenance: Adjusted connection pool settings to handle more simultaneous connections without breaking a sweat.
    • Swim Coach Monitoring: Set up real-time monitoring for the connection pool to give us an early warning if it starts feeling overwhelmed.
  • Short-Term:

    • Auto-Pool Inflator: Developing an automated system to inflate or deflate the connection pool as needed, like a pool float.
    • Super Soaker Load Testing: Created thorough load testing scenarios to ensure our connection pool can handle the splash of user activity.
  • Long-Term:

    • Global Pool Domination: Exploring multi-region database setups to distribute the pool load worldwide and prevent pool parties from getting out of hand.
    • Ninja Incident Response: Training our engineers to be incident response ninjas – fast, efficient, and ready to tackle any gremlins that come their way.

So, here’s to a future where our CSS connection pool parties are legendary and the only slowdown is when we’re sipping smoothies by the virtual poolside. Cheers!


In the world of modern business and technology, incidents are a reality that organizations must face. However, through the practice of incident postmortems, these incidents can be transformed from setbacks into opportunities for growth and improvement. By dissecting and analyzing incidents, organizations can unearth valuable insights, fortify their systems, and enhance overall operational efficiency. The art of writing an effective incident postmortem lies in its ability to combine technical precision with a forward-looking mindset, paving the way for a more resilient and successful future.

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