This issue starting to happen for me after upgrade from Wily to Xenial. Bunch of VMs have org.qemu.guest_agent.0 channel unable to start after upgrade with same error in syslog. On other hand, VMs without org.qemu.guest_agent.0 channel working. As workaround, removing org.qemu.guest_agent.0 channel from all VMs make it works without errors.
This issue starting to happen for me after upgrade from Wily to Xenial. Bunch of VMs have org.qemu. guest_agent. 0 channel unable to start after upgrade with same error in syslog. On other hand, VMs without org.qemu. guest_agent. 0 channel working. As workaround, removing org.qemu. guest_agent. 0 channel from all VMs make it works without errors.