This is most probably because you are using ZFS 0.7.x user space tools with a kernel that has ZFS 0.6.5.x drivers. Please install the latest Bionic 4.15 kernel and see if that fixes the issue.
This is most probably because you are using ZFS 0.7.x user space tools with a kernel that has ZFS 0.6.5.x drivers. Please install the latest Bionic 4.15 kernel and see if that fixes the issue.