Check /var/log/dpkg for the gritty details. Currently the IPC protocol used between the init daemon and other utilities isn't stable, so the versions of both must be exactly matched.
If the upgrade broke half way, you probably had different versions of upstart (/sbin/init) and upstart-compat-sysv (/sbin/shutdown), so they couldn't communicate. -- Fail to reboot after upgrading from 0.2.7-7 to 0.3.1-1 https://launchpad.net/bugs/75680 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
