Comment 3 for bug 1860762

I was able to fix this error:

 E: mkinitramfs failure cpio 141 lz4 -9 -l 24

by deleting the snapshots that sanoid made *during* the installation process:

sarnold@millbarge:/boot$ sudo zfs destroy bpool@autosnap_2020-01-24_04:00:05_hourly%autosnap_2020-01-24_08:45:05_frequently
[sudo] password for sarnold:
sarnold@millbarge:/boot$ sudo zfs destroy bpool/BOOT@autosnap_2020-01-24_04:00:05_hourly%autosnap_2020-01-24_08:45:05_frequently
sarnold@millbarge:/boot$ sudo zfs destroy bpool/BOOT/ubuntu@autosnap_2020-01-24_04:00:05_hourly%autosnap_2020-01-24_08:45:05_frequently
sarnold@millbarge:/boot$ df -h .
Filesystem Size Used Avail Use% Mounted on
bpool/BOOT/ubuntu 365M 156M 210M 43% /boot
sarnold@millbarge:/boot$ sudo dpkg --configure -a
Setting up initramfs-tools (0.133ubuntu10) ...
update-initramfs: deferring update (trigger activated)
Processing triggers for initramfs-tools (0.133ubuntu10) ...
update-initramfs: Generating /boot/initrd.img-5.3.0-29-generic
cryptsetup: ERROR: Couldn't resolve device rpool/ROOT/ubuntu
cryptsetup: WARNING: Couldn't determine root device
sarnold@millbarge:/boot$

Considering sanoid is not packaged in Ubuntu, there may not be anything that do-release-upgrade or initramfs-tools can do differently.

Thanks