On May 22, 2012, John Allspaw wrote about “blameless postmortems” on Etsy’s engineering blog, Code as Craft. He described a familiar cycle after a failure. The “Engineer is punished, shamed, blamed, or retrained.” Engineers then “become silent on details,” and the result is “Cover-Your-Ass” engineering.
In a blameless postmortem, the engineer gives a detailed account of what happened “without fear of punishment or retribution.” The aim is to learn how the failure happened.
Allspaw gave the method a name because, as he described it, the familiar response to failure is to name, blame and shame.