The /etc/cron.daily/apt script, which I believe handles the automatic update setting, was not marked executable on either machine.
This reveals two problems:
- /etc/cron.daily/apt lost its executable status during the do-release-upgrade process (I'm quite sure I didn't change the permissions on that file myself)
- The GUI for configuring the automatic update interval should check this and warn you if this script is not executable! (Or just fix it itself.)
Found the problem (I think).
The /etc/cron.daily/apt script, which I believe handles the automatic update setting, was not marked executable on either machine.
This reveals two problems:
- /etc/cron.daily/apt lost its executable status during the do-release-upgrade process (I'm quite sure I didn't change the permissions on that file myself)
- The GUI for configuring the automatic update interval should check this and warn you if this script is not executable! (Or just fix it itself.)