The issue here is not that the error message is unclear; the issue is that update-manager is being run with $DISPLAY unset, when this shouldn't ever happen on the desktop. So something is wrong in the privilege handling stack when we try to do a partial upgrade.
The issue here is not that the error message is unclear; the issue is that update-manager is being run with $DISPLAY unset, when this shouldn't ever happen on the desktop. So something is wrong in the privilege handling stack when we try to do a partial upgrade.