unattended update fails to complete

[Nigel Reed]

Symptom: unable to install packages, getting the error
Witing for cache lock: Could not get lock /var/lib/dpkg/lock-frontend. It is held by process <pid> (unattended-upgr)

root@wibble:/var/lib/samba# ps -ef|grep apt
root 412197 1 0 06:37 ? 00:00:00 /bin/sh /usr/lib/apt/apt.systemd.daily install
root 412201 412197 0 06:37 ? 00:00:00 /bin/sh /usr/lib/apt/apt.systemd.daily lock_is_held install
root 425404 1 0 13:01 ? 00:00:00 /bin/sh /usr/lib/apt/apt.systemd.daily update

Cause:
It appears an unattended update failed to complete due to a process that doesn't terminate.

root@wibble:/etc/ssh# pstree -als 420420
systemd splash
  └─apt.systemd.dai /usr/lib/apt/apt.systemd.daily install
      └─apt.systemd.dai /usr/lib/apt/apt.systemd.daily lock_is_held install
          └─unattended-upgr /usr/bin/unattended-upgrade
              └─unattended-upgr /usr/bin/unattended-upgrade
                  └─dpkg --status-fd 11 --configure --pending
                      └─linux-image-5.1 /var/lib/dpkg/info/linux-image-5.13.0-28-generic.postinst triggered linux-update-5.13.0-28-generic
                          └─sh /usr/lib/linux/triggers/5.13.0-28-generic
                              └─run-parts --report --exit-on-error --arg=5.13.0-28-generic --arg=/boot/vmlinuz-5.13.0-28-generic /etc/kernel/postinst.d
                                  └─grub-mkconfig /usr/sbin/grub-mkconfig -o /boot/grub/grub.cfg
                                      └─30_os-prober /etc/grub.d/30_os-prober
                                          └─30_os-prober /etc/grub.d/30_os-prober
                                              └─paste -s -d

It appears that something in os-prober is hanging.

[Paul White (paulw2u)]

We are sorry that we do not always have the capacity to review all reported bugs in a timely manner. You reported this bug some time ago and there have been many changes in Ubuntu since that time.

Please note that I don't see anything that confirms the release of Ubuntu you were using when you raised this bug report although 'Impish' is implied from the kernel version shown in the bug description. Also bug reports need to be reported against the affected package rather than against the Ubuntu project in general if they are to reach someone from a team that maintains the affected package.

Do you still see a problem related to the one that you reported when using a currently supported version of Ubuntu? Please let us know if you do otherwise this report can be left to expire in approximately 60 days time.

Thank you for helping make Ubuntu better.

[Launchpad Janitor (janitor)]

[Expired for Ubuntu because there has been no activity for 60 days.]