Newer versions of UpdateManager.Core.UpdateList (in python3-update-manager) try reading /etc/machine-id first and only fall back to /var/lib/dbus/machine-id, but the trusty version unconditionally opens /var/lib/dbus/machine-id (and fails if dbus is not installed and consequently that file does not exist).
I do not think that backporting this change will be sufficient, because you cannot guarantee that /etc/machine-id exists on a trusty system.
Newer versions of UpdateManager. Core.UpdateList (in python3- update- manager) try reading /etc/machine-id first and only fall back to /var/lib/ dbus/machine- id, but the trusty version unconditionally opens /var/lib/ dbus/machine- id (and fails if dbus is not installed and consequently that file does not exist).
I do not think that backporting this change will be sufficient, because you cannot guarantee that /etc/machine-id exists on a trusty system.