On a KVM host, after gracefully shutting down the guest KVM, I get:
[root@kvm]# /sbin/shutdown -h now Broadcast message from email@example.com (/dev/pts/1) at 15:23 ... The system is going down for halt NOW! **shutdown: Method "EmitEvent" with signature "sasb" on interface "com.ubuntu.Upstart0_6" doesn't exist**
And I cannot reboot the machine. The same happens for -Ph or -r.
UPDATE 1: I will place this question on hold until the next time I have to restart this machine.