It's failing during an upgrade. My guess would be that it's a systemd problem, but one triggered by mixing systemd versions. Probably the systemctl from Fedora

It's failing during an upgrade. My guess would be that it's a systemd problem, but one triggered by mixing systemd versions. Probably the systemctl from Fedora 21 does something that the systemd from Fedora 20 doesn't like. If that's the case, the bug might have even already been fixed in systemd upstream, but the fix wasn't applied to the older systemd in Fedora 20. The solution would be to backport the fix to Fedora 20's systemd package, so users who do a "yum update" before upgrading to Fedora 21 would have it. An alternative workaround might be to, immediately after unpacking the new systemd, send a SIGTERM to PID 1. According to http://www.freedesktop.org/software/systemd/man/systemd.html http://www.freedesktop.org/software/systemd/man/systemd.html, that signal directly tells PID 1 to re-exec itself, without using systemctl in the process. That would make PID 1 be the new systemd before anything tries to use the new systemctl.