Comment 12 for bug 440179

I'm also seeing this with several guest machines that I moved to a different host. I change the networking config and then this started to occur. I removed two NICs and added a new one. It currently has only one NIC. This was needed for virt-manager to associate the guest with the proper network on the host. After getting the message I modified /etc/networking/interfaces and /etc/udev/rules.d/70-persistent-net.rules to get my NIC working as expected, but the errors still show up.

'/etc/init.d/networking restart' works

'service networking restart' does not work. It simply fails with the "Unknown instance:" message.

If I run 'initctl list | grep network' I see only the current interfaces, but I see a line that says "networking stop/waiting" so I think this confirms Watte's assumption that those results were a symptom, not cause.