A pre-mortem has to treat the failure as certain and ask why it happened; asking what could go wrong is too tentative to work.

One of the mistakes is that they just frame it wrong from the beginning. They'll say, "Okay, we should do a pre-mortem. So, what can go wrong?" It's not an issue of what can go wrong. We're dealing with a crystal ball that has showed that the plan has failed. We know that it failed. And our job is is to explain why. So, saying what can go wrong is too tentative. It's too vague.