[Bug 1992513] Re: apt will not install nvidia-driver-470-server if nvidia-driver-450-server is installed and out of date

[Julian Andres Klode]

I'm going to set this to Won't Fix because that seems to be an important
part of the solver logic, and the workarounds - running upgrade first,
or using ubuntu-drivers - are easy to do and the potential for
regression significantly outweighs them.

This will get solved eventually by a nicer solver (a proper optimization
solver) sure, if we make it there. Lots of caveats because I'm not that
clever that I want to write a competitive partial weighted maxsat or
linear programming solver, so end up reusing libraries, and neither z3
nor clasp are exactly optimal (also figuring out how to get them to
explain uninstallability is hard).

On the other hand, I am also exploring preventing the solver (both old
and new) from removing packages due to Conflicts, so removals can only
happen as part of a dist-upgrade or an explicit removal request, to
further reduce issues with people breaking their systems by accidentally
removing half of it (caveats as to the scope with manually vs
automatically installed packages, and whether packages are not needed
anymore are to be).

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https://bugs.launchpad.net/bugs/1992513

Title:
  apt will not install nvidia-driver-470-server if nvidia-
  driver-450-server is installed and out of date

Status in apt package in Ubuntu:
  Won't Fix
Status in nvidia-graphics-drivers-450-server package in Ubuntu:
  New
Status in nvidia-graphics-drivers-470-server package in Ubuntu:
  New

Bug description:
  apt/jammy

  apt will refuse to install nvidia-driver-470-server if nvidia-driver-450-server is installed *and* out of date. I can reproduce this by disabling all but the jammy release pocket, installing the old n-d-450-s from there, and then enabling updates and trying to install n-v-470-s (where a new
  n-d-450-s is available):

  # libnvidia-gl-450-server has an update available
  root at dannf-apt-jammy:/var/cache# apt install --dry-run libnvidia-gl-470-server -o Debug::pkgProblemResolver=yes
  Reading package lists... Done
  Building dependency tree... Done
  Reading state information... Done

  Some packages could not be installed. This may mean that you have
  requested an impossible situation or if you are using the unstable
  distribution that some required packages have not yet been created
  or been moved out of Incoming.
  The following information may help to resolve the situation:

  The following packages have unmet dependencies:
   libnvidia-common-450-server : Conflicts: libnvidia-common
   libnvidia-common-470-server : Conflicts: libnvidia-common
  E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.

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