While ZFS has a well-earned reputation for data integrity and reliability, ZFS native encryption has some incredibly sharp edges that will cut you if you don't know where to be careful. Unfortunately, I learned this the hard way, standing in a pool of my own blood and tears after thoroughly lacerating myself. I very nearly permanently lost 8.5 TiB of data after performing what should've been a series of simple, routine ZFS operations but resulted in an undecryptable dataset. Time has healed the wound enough that I am no longer filled with anguish just thinking about it, so I will now share my experience in the hope that you may learn from my mistakes. Together, we'll go over the unfortunate series of events that led to this happening and how it could've been avoided, learn how ZFS actually works under the hood, use our newfound knowledge to debug and reproduce the issue at hand, and finally compile a modified version of ZFS to repair the corrupted state and rescue our precious data. This is the postmortem of that terrible, horrible, no good, very bad week…