Whether you run a service or provide a product to customers, there will be times when your service (or part of it) is unexpectantly unavailable. These things happen however providing a good post mortem can demonstrate transparency and build trust with your customers if executed correctly.
Leave blame at the door
If you don’t already use blameless post mortems, I suggest you go check out some articles from Etsy and Mathias Meyer as blameless post mortems will change the way you and your team view incidents. Instead of blaming individual people or tools, you will look to build an environment where people are safe to fail and people won’t be petrified of change. This type of environment will encourage people to discuss the problems and the best approach to solving them instead of throwing each other under the bus to avoid getting fired.
Giving your customers a sincere apology is one of the most important things you can do for your post mortem. It shows you are human and it demonstrates you understand the impact your incident had on them and that you want to make it right.
Your apology should feature within the first paragraph (or there abouts) of the post mortem - giving an apology within the last sentence of your report isn’t good enough.
Provide a summary and technical account of the events
Despite what industry you are in there will always be a varied skill level of people reading your post mortem - which is why it’s important to include a summary of the events (usually in layman terms) and a nice technical dive into the incident itself. You should cover what components were affected as well as the steps taken during your diagnosis and investigation.
Another good use of this section is to provide a high level insight into how various parts of your service or products interact together. People love this type of insight and it offers the opportunity to turn this negative experience into a positive learning experience for the reader.
For many people, this will be the most important section of your post mortem as they want to see what steps you are taking to prevent this incident from happening again. If you are writing a post mortem and don’t provide action items to remedy the situation, you are showing you are not committed to mitigating the problem from reoccurring and your customers are likely to take their business elsewhere.