/usr/share/unattended-upgrades/unattended-upgrade-shutdown:ProcessLookupError:/usr/share/unattended-upgrades/unattended-upgrade-shutdown@170:signal_stop_unattended_upgrade

[errors.ubuntu.com bug bridge]

The Ubuntu Error Tracker has been receiving reports about a problem regarding unattended-upgrades. This problem was most recently seen with package version 1.1ubuntu1.18.04.5, the problem page at https://errors.ubuntu.com/problem/12ed316a816a195a30f4c94945e701443268e68b contains more details, including versions of packages affected, stacktrace or traceback, and individual crash reports.
If you do not have access to the Ubuntu Error Tracker and are a software developer, you can request it at http://forms.canonical.com/reports/.

[Launchpad Janitor (janitor)]

This bug was fixed in the package unattended-upgrades - 1.7

---------------
unattended-upgrades (1.7) unstable; urgency=medium

  [ Nils Toedtmann ]
  * Clarify 'A reboot is required' warning, that the requirement might stem
    from a previous run

  [ Balint Reczey ]
  * Build depend on and run pycodestyle, the replacement of pep8
  * autopkgtest: Clean up after failed debootstrap to retry cleanly
  * Handle when unattended-upgrades stopped without
    unattended-upgrade-shutdown sending SIGTERM (LP: #1795657)
  * Don't crash on missing dpkg log file (LP: #1795692)
  * do_auto_remove() is successful unless a commit() operation fails
    (LP: #1795696)
  * Check only dowloaded .deb files for conffile prompts (LP: #1796100)
  * Recommend systemd-sysv as the first alternative of cron.
    Unattended-upgrades is started via systemd timers or by the .service file
    on the default Debian and Ubuntu installations without cron's involvement.
    Systems without systemd-sysv can still install unattended-upgrades and run
    it via cron.
  * Only suggest python3-gi and skip check for metered connection when it is
    missing (Closes: #909543)
  * Only suggest powermgmt-base amd skip checking power status when it is not
    present
  * Show message about missing optional dependencies only once
  * Add configuration file option to enable verbose and debug logging.
    Thanks to Paul Wise
  * Revert to running unattended-upgrades.service in multi-user.target
  * Trigger unattended-upgrade-shutdown actions with PrepareForShutdown()
    Performing upgrades in service's ExecStop did not work when the upgrades
    involved restarting services because systemd blocked other stop/start
    actions making maintainer scripts time out and be killed leaving a broken
    system behind.
    Running unattended-upgrades.service before shutdown.target as a oneshot
    service made it run after unmounting filesystems and scheduling services
    properly on shutdown is a complex problem and adding more services to the
    mix make it even more fragile.
    The solution of monitoring PrepareForShutdown() signal from DBus
    allows Unattended Upgrade to run _before_ the jobs related to shutdown are
    queued thus package upgrades can safely restart services without
    risking causing deadlocks or breaking part of the shutdown actions.
    Also ask running unattended-upgrades to stop when shutdown starts even in
    InstallOnShutdown mode and refactor most of unattended-upgrade-shutdown to
    UnattendedUpgradesShutdown class. (LP: #1778219)
  * Handle reverting to WantedBy=multi-user.target when upgrading from 1.5 or
    1.6
  * debian/postinst: Redirect stdout from systemctl and deb-systemd-invoke to
    stderr and skip running systemctl start unattended-upgrades.service when
    unattended-upgrades is already running to avoid deadlock.
  * Increase logind's InhibitDelayMaxSec to 30s.
    This allows more time for unattended-upgrades to shut down gracefully
    or even install a few packages in InstallOnShutdown mode, but is still a
    big step back from the 30 minutes allowed for InstallOnShutdown previously.
    Users enabling InstallOnShutdown node are advised t...