I'm having trouble booting a previously bootable system.
This system has been in use since very shortly before the Stretch release and has always been Stretch.
I'm using Grub to boot a fully encrypted system. Each drive is partitioned with GPT and encrypted using LUKS. The drives are then used together with BTRFS.
This system has worked with some minor boot problems (Which I thought were fixed by adding the bios_grub flag to my partition and the pmbr_boot flag to my disk) for at least a year.
Today I can not boot the system. I suspect I've made it worse for trying to repair it so I will jump to where I am now.
When I boot I get on either device:
error: no such device: (UUID of my decrypted luks volume / btrfs pool)
error: unknown filesystem