The Premortem

A few years before the scheduler project, the marketplace moved its services from an old logging system to a new one. Four teams reviewed the plan and approved it. Two quarters later, 80 percent of services had moved, and then the work stopped. The remaining services belonged to teams with other priorities, and two of those teams needed a feature the new system did not have.

Both logging systems still run today, with two bills and two on-call rotations. When the platform group later reviewed what had happened, several engineers said they had expected it