Remove 'binfmt-support' package and tried upgrade again. Slightly different error message from 'systemctl status libvirt-bin.service' this time with addition of a 'NOTCONFIGURED' message:
Jun 27 22:57:22 lydia systemd[1]: libvirt-bin.service: Main process exited, code=exited, status=6/NOTCONFIGURED
Jun 27 22:57:22 lydia systemd[1]: Failed to start Virtualization daemon.
Jun 27 22:57:22 lydia systemd[1]: libvirt-bin.service: Unit entered failed state.
Jun 27 22:57:22 lydia systemd[1]: libvirt-bin.service: Failed with result 'exit-code'.
Jun 27 22:57:22 lydia systemd[1]: libvirt-bin.service: Service hold-off time over, scheduling restart.
Jun 27 22:57:22 lydia systemd[1]: Stopped Virtualization daemon.
Jun 27 22:57:22 lydia systemd[1]: libvirt-bin.service: Start request repeated too quickly.
Jun 27 22:57:22 lydia systemd[1]: Failed to start Virtualization daemon.
Remove 'binfmt-support' package and tried upgrade again. Slightly different error message from 'systemctl status libvirt- bin.service' this time with addition of a 'NOTCONFIGURED' message:
Jun 27 22:57:22 lydia systemd[1]: libvirt- bin.service: Main process exited, code=exited, status= 6/NOTCONFIGURED bin.service: Unit entered failed state. bin.service: Failed with result 'exit-code'. bin.service: Service hold-off time over, scheduling restart. bin.service: Start request repeated too quickly.
Jun 27 22:57:22 lydia systemd[1]: Failed to start Virtualization daemon.
Jun 27 22:57:22 lydia systemd[1]: libvirt-
Jun 27 22:57:22 lydia systemd[1]: libvirt-
Jun 27 22:57:22 lydia systemd[1]: libvirt-
Jun 27 22:57:22 lydia systemd[1]: Stopped Virtualization daemon.
Jun 27 22:57:22 lydia systemd[1]: libvirt-
Jun 27 22:57:22 lydia systemd[1]: Failed to start Virtualization daemon.