Posted on Wed 28 March 2018
Useful tip (for me): any time ZFS emits internal error: Invalid argument, what it probably means is that the DKMS module and the userland utilities are different versions.
sudo modinfo zfs|head
will tell you what version your kernel is using; apt show -a zfsutils-linux
will tell you what versions of the user commands are available. Look for a mismatch.