Comment 5 for bug 1581640

I got the bug during update from 15.10 to 16.04 gnome flavoured ubuntu (amd64)

the error was something like:
failed to install systemd exit code 2

and all the depending packages (including gnome itself) failed due to dependency problems

the distro-upgrade ended with a partial rollback.

Before reboot I did an
dpkg --configure -a
    which resulted in: too many errors, break
So I tried
apt-get install systemd
    which worked perfectly
and afterwards I did
apt-get update
apt-get upgrade
    and my distro-upgrade was fine

PS sorry for not havin noted down the exact error messages, I was panicking a little