Comment 15 for bug 1778817

syslog search for 'inhibit':

$ zgrep -i inhibit /var/log/syslog.*
/var/log/syslog.5.gz:Jun 26 11:56:40 epona org.freedesktop.Notifications[1961]: ** (notify-osd:2212): WARNING **: dnd_is_idle_inhibited(): got error "No such method 'IsInhibited'"
$

so, not interesting.

/var/log/dist-upgrade/main.log attached. Critical section is:

2018-06-26 15:30:27,637 DEBUG found components: {'bionic': {'universe', 'multiverse', 'main', 'restricted'}, 'bionic-security': {'universe', 'multiverse', 'main', 'restricted'}, 'bionic-updates': {'universe', 'multiverse', 'main', 'restricted'}}
2018-06-26 15:55:19,566 DEBUG plugins for condition 'StartUpgrade' are '[]'
2018-06-26 15:55:19,567 DEBUG plugins for condition 'bionicStartUpgrade' are '[]'
2018-06-26 15:55:19,567 DEBUG plugins for condition 'from_xenialStartUpgrade' are '[]'
2018-06-26 15:55:19,567 DEBUG quirks: running StartUpgrade
[...]
2018-06-26 15:55:19,571 DEBUG killing update-notifier
2018-06-26 15:55:19,587 DEBUG killing kblueplugd kbluetooth4
2018-06-26 15:55:19,605 DEBUG killing gnome-screensaver
2018-06-26 15:55:19,614 DEBUG setup poke timer for the scrensaver
2018-06-26 15:55:19,626 DEBUG inhibit gnome-session idle
2018-06-26 15:55:19,630 DEBUG apt btrfs snapshots supported: False
2018-06-26 15:55:19,630 INFO cache.commit()
2018-06-26 15:55:19,630 DEBUG failed to SystemUnLock() (E:Not locked)
2018-06-26 16:17:28,618 DEBUG got a conffile-prompt from dpkg for file: '/etc/ssh/ssh_config'

I'm not sure, could the problem be that the inhibit was not emitted until long after the last prompt before the upgrade started?