upgrades fail with errors of the form apt: unknown dependency error

[Alok G Singh]

While running an upgrade, we see errors of the form

apt: unknown dependency error

This is very similar to the error in lp:1668583 and using "Request upgrade" which runs dist-upgrade does allow upgrades to complete.

Looking for sources in backports does not throw up anything.

$ for in in $(COLUMNS=200 dpkg -l | awk '{print $2}')
do
apt-cache policy $i | awk '/500 http/ { print $3 }'
done | sort -u

stable/main
xenial/main
xenial/multiverse
xenial/restricted
xenial-security/main
xenial-security/multiverse
xenial-security/restricted
xenial-security/universe
xenial/universe
xenial-updates/main
xenial-updates/multiverse
xenial-updates/pike/main
xenial-updates/restricted
xenial-updates/universe

$ lsb_release -rd
Description: Ubuntu 16.04.6 LTS
Release: 16.04

$ apt policy landscape-client
landscape-client:
  Installed: 17.03~bzr940-0~941~ubuntu16.04.1
  Candidate: 17.03~bzr940-0~941~ubuntu16.04.1
  Version table:
 *** 17.03~bzr940-0~941~ubuntu16.04.1 500
        500 http://ppa.launchpad.net/landscape/17.03/ubuntu xenial/main amd64 Packages
        100 /var/lib/dpkg/status
     16.03-0ubuntu2.16.04.6 500
        500 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages
     16.03-0ubuntu2 500
        500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages

[Alok G Singh (alephnull-b)]

Subscribing field-medium as this is blocking security updates for customer clouds.

[Adam Collard (adam-collard)]

Why do you have 17.03 PPA in sources.list?

[Alok G Singh (alephnull-b)]

@Adam, that's a good question. I am attempting to figure it out.

[Launchpad Janitor (janitor)]

[Expired for landscape-client (Ubuntu) because there has been no activity for 60 days.]