I had the same issues on one of my computers and it behaved exactly as described above: Nor root device found (USB keyboard unusable) update-initramfs destroyed any initrd.img it touched with udev 240-2 a downgrade to 239-8 (the last I could get my hands on quickly) resolved the issue
The system is a Dell T5810 with a 6 core Xeon and an Intel 750 NVME fstab: # / was on /dev/nvme0n1p2 during installation UUID=d70e9492-f746-4b89-b137-fa6d96af1430 / ext4 errors=remount-ro 0 1 # /boot/efi was on /dev/nvme0n1p1 during installation UUID=36E5-0424 /boot/efi vfat umask=0077 0 1 # UUID=6EDB-422E /boot/efi vfat umask=0077 0 1 # /data was on /dev/sdc3 during installation UUID=95266c1f-9843-4a91-b57c-47c2d27348be /data ext4 defaults 0 2 # /home was on /dev/nvme0n1p4 during installation UUID=d6ead145-584c-49e5-a85b-182a55187f68 /home ext4 defaults 0 2 # swap was on /dev/nvme0n1p3 during installation UUID=7b37bd7c-f7d1-45eb-a228-07a7a77ae1e4 none swap sw 0 0 regards Martin