I just found out that unattended upgrade to the 8.2 point release breaks cron when running systemd. This was already mentioned in the cron bug that is fixed in the point release, but somehow didn't get a followup then: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=783683#57
The bug that is fixed is that cron.service had the default KillMode=control-group that kills all the processes in the control group when cron is restarted and the update fixes this by setting KillMode=process. The problem with unattended-upgrades or anything else that is started by cron and does the upgrade is that when it upgrades cron, then cron is stopped using the old configuration, killing unattended-upgrades and dpkg, leaving the system with a cron package in a broken state. So if you are running Jessie with systemd and have configured unattended-upgrades to also automatically install non-security updates then cron will very likely be broken on all your systems. You can fix it by running "dpkg --configure -a" and "apt-get --reinstall install cron". The good part is that only security updates are enabled by default by unattended-upgrades, but my guess is that I'm not the only one who has non-security updates enabled in unattended-upgrades. There is also no way for us to automatically fix this because cron isn't running anymore on those systems. How do we let people know that they need to check their systems and manually fix them by running "dpkg --configure -a" and "apt-get --reinstall install cron"? Because until they do they also won't get any automatic security updates... Kind regards, Jeroen Dekkers
