Phased updates block release upgrades

[Alkis Georgopoulos]

I updated my Kubuntu 23.04 to 23.10 using do-release-upgrade. It finished 100% successfully. But after rebooting into 23.10, I noticed that network-manager was kept back to the 23.04 version due to phased updates. Specifically:

# apt policy network-manager

network-manager:
  Installed: 1.42.4-1ubuntu2
  Candidate: 1.44.2-1ubuntu1.2
  Version table:
     1.44.2-1ubuntu1.2 500 (phased 70%)
        500 http://gr.archive.ubuntu.com/ubuntu mantic-updates/main amd64 Packages
     1.44.2-1ubuntu1 500
        500 http://gr.archive.ubuntu.com/ubuntu mantic/main amd64 Packages
 *** 1.42.4-1ubuntu2 100
        100 /var/lib/dpkg/status

I.e. the phased version (1.44.2-1ubuntu1.2) prevents me from getting the current mantic version (1.44.2-1ubuntu1) and I'm stuck with the lunar version (1.42.4-1ubuntu2).

[Julian Andres Klode (juliank)]

There isn't anything we can do in apt about this sadly. The implementation that would work correctly for this case (which uses pinning to implement phasing) breaks the solver in most cases.

Trying to switch candidates in the upgrader code is also not something I'd be interested in, it would likely again break systems.

Hence reassigning this to ubuntu-release-upgrader to do set the always-include-phased-updates option (don't remember full name, lookup phased update in apt discourse post) in apt_pkg.config object.

The pinning based implementation that would solve this particular issue is also available via a configuration option but it would break the solver as soon as lunar-updates had a newer version than mantic-updates for one binary and we try to install another binary of the same source package.

This means people upgrading releases get phased upgrades installed. Sadly it's an all or nothing right now, and no phased upgrades doesn't work in this particular case as it has the same behaviour as the bug.

The real solution involves writing a new solver that doesn't just remove packages due to unsatisfied dependencies, which is somewhat in progress (see https://salsa.debian.org/apt-team/solver3 for the concepts) and then we can be happy.

[Alkis Georgopoulos (alkisg)]

👍

- launchpad should really get a "like/thumbs up" button, to react to posts without spamming! :D
- The proposed solution sounds good enough for now, release upgrades is probably the most common cause for this issue and the most significant one as it might break the upgrade due to unsatisfied dependencies.