Comment 2 for bug 1778800

Could you please confirm that the installation failure happened during shutdown? In that case this is a duplicate of LP: #1778219.

DpkgTerminalLog.txt:
Setting up unattended-upgrades (1.1ubuntu1.18.04.1) ...
Failed to start unattended-upgrades.service: Connection timed out
See system logs and 'systemctl status unattended-upgrades.service' for details.
invoke-rc.d: initscript unattended-upgrades, action "start" failed.
● unattended-upgrades.service - Unattended Upgrades Shutdown
   Loaded: loaded (/lib/systemd/system/unattended-upgrades.service; enabled; vendor preset: enabled)
   Active: active (running) since Mon 2018-06-25 07:02:10 BST; 1 day 15h ago
     Docs: man:unattended-upgrade(8)
   CGroup: /system.slice/unattended-upgrades.service
Failed to dump process list, ignoring: No such file or directory
dpkg: error processing package unattended-upgrades (--configure):
 installed unattended-upgrades package post-installation script subprocess returned error exit status 1

... however there is a little twist, since in u-u's case the debhelper-added service start is not needed and I'm fixing that.