// Lesson 1 of 1 · ~25 min · Intermediate

Blameless incidents and DORA metrics

After this lesson you can decide when an incident needs a postmortem, write one without blame, and read your team’s delivery through the DORA metrics.

You will be able to

Apply the SRE book’s postmortem triggers
Turn blame into system-focused findings
Match each DORA metric to what it measures

Warm-up · Activity 1 of 7
Warm-up: after a bad deploy, what is usually the fastest way to restore service?
Find out who wrote the changeRoll back to the last known good versionWait for traffic to dropWrite the postmortem first
Predict · Activity 2 of 7
Decide: which of these incidents meet the postmortem triggers listed in the Google SRE book? Pick all that apply.
Select all that apply.
A migration silently deleted 200 customer notesA test failed in CI and the change never mergedThe on-call engineer had to roll back a release at 02:00Checkout was unavailable to users for 40 minutes
Practice · Activity 3 of 7
Which sentence belongs in a blameless postmortem?
“Nobody was at fault, so there is nothing to change.”“The deploy script accepted a production config without validation, so a typo reached every region at once.”“Alex pushed a broken config and should have been more careful.”“The team was careless during the release.”
Practice · Activity 4 of 7
Match each DORA metric to what it measures.
Change lead time — Match for “Change lead time”
Deployment frequency — Match for “Deployment frequency”
Failed deployment recovery time — Match for “Failed deployment recovery time”
Change fail rate — Match for “Change fail rate”
Deployment rework rate — Match for “Deployment rework rate”
Practice · Activity 5 of 7
Last month: 40 deployments, 6 of which needed a rollback or hotfix. What is the change fail rate, as a percentage?
Your answer %
Brain teaser · Activity 6 of 7
Brain teaser. A manager sets a target: “Cut change fail rate in half this quarter.” The team hits it by deploying once a month instead of daily. What happened to the other metrics?
Recovery time must have improved tooEverything improvedNothing else changedDeployment frequency fell and change lead time grew: throughput was traded away
Apply · Activity 7 of 7
Mini-task. Write a one-page postmortem outline for: “A config typo took the API down for 25 minutes; on-call rolled back.” Use headings.
Check your work against this list
- It has an impact section with duration and who was affected
- It has a timeline from detection to recovery
- The contributing causes are about systems and processes, and name no person
- Each action item has an owner and a due date
- It says what went well, not only what went wrong

Exit ticket

5 questions, no hints. Score 80% or more to complete the lesson.

Finish every activity above to unlock the exit ticket.

Key ideas

Blameless means fixing systems, not people

The Google SRE book describes a blameless postmortem as one that focuses on the contributing causes of an incident without pointing at any individual or team for bad or inappropriate behaviour. It assumes everyone acted with good intentions on the information they had. People who fear punishment hide the details you need.

Agree the triggers in advance

Common triggers listed in the SRE book include user-visible downtime or degradation beyond a threshold, data loss of any kind, on-call engineer intervention such as a rollback or rerouting traffic, a resolution time above a threshold, and a monitoring failure, which usually means a person found the incident rather than an alert. Any one is enough. Deciding these beforehand removes the awkward “does this one count?” debate, and any stakeholder can still ask for a postmortem.

Measure the delivery system

DORA’s software delivery metrics are change lead time, deployment frequency, failed deployment recovery time, change fail rate and deployment rework rate. They describe the team’s delivery system, not individuals, so use them to find bottlenecks, never to rank people.

Sources

Last reviewed September 28, 2026

Blameless incidents and DORA metrics

Warm-up: after a bad deploy, what is usually the fastest way to restore service?

Decide: which of these incidents meet the postmortem triggers listed in the Google SRE book? Pick all that apply.

Which sentence belongs in a blameless postmortem?

Match each DORA metric to what it measures.

Last month: 40 deployments, 6 of which needed a rollback or hotfix. What is the change fail rate, as a percentage?

Brain teaser. A manager sets a target: “Cut change fail rate in half this quarter.” The team hits it by deploying once a month instead of daily. What happened to the other metrics?

Mini-task. Write a one-page postmortem outline for: “A config typo took the API down for 25 minutes; on-call rolled back.” Use headings.