Undetanding Postmortem Culture: Learning from Failure


What is post-mortem ?

A post-mortem is a document that summarizes the effects of an incident on a system, actions taken to mitigate or resolve it, the cause of the incident, and measures to prevent recurrence.

Difference from trouble report

A post-mortem is similar in content to the trouble report, but it has a different purpose than the reader.
A failure report is a report that explains to a user who has suffered a disadvantage due to the occurrence of a failure. Post-mortem, on the other hand, is a report to learn from disabilities and improve service. Therefore, the reader is a relative engineer. It is an incident summary.


Created date:
Root cause:
Occurrence factor:
action item:

Important things to do in post-mortem

Do not criticize

This is the most important thing. When criticized, the person who made the mistake is afraid of punishment and speaks nothing, unaware of the true cause behind it. Then you would not be able to learn from the disability that is the purpose of the post-mortem. It is important to focus on cause analysis and improvement rather than criticism.

Thoroughly analyze and understand the root cause of the disorder

Inadequate analysis of a failure can lead to incorrect recurrence prevention measures, resulting in the same failure recurrence. It is important to keep asking questions objectively and simply when you analyze.

Solve by mechanism, not by people

The conclusion that recurrence prevention measures are “careful” or “do your best” will be resolved by relying on people, but people cannot be easily “corrected”. Instead, it’s important to modify systems and processes to help people make the right choices.

Share knowledge with many people

Disability cause analysis and recurrence prevention measures are a collection of knowledge learned from disability. That knowledge would be know-how that can be utilized by other teams. Since the purpose of post-mortem is to improve services, it is important to share knowledge more and more.

How to practice

Determine the criteria for writing post-mortems

Postmortems spend a fair amount of time and effort, making it impractical to address all obstacles. Therefore, it is necessary to decide the judgment criteria.

Continuing activities to take root in culture

In order to take root in the culture of writing post-mortems, it is good to have a post-mortem reading party that looks back on past post-mortems, or a bad luck circle that role-plays past post-mortems.




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80% is the creation, the rest is depression. Frontend developer and data scientist, designer. Looking for Physics Ph.D Twitter: @_t_i_show