This bug was fixed in the package apt - 3.1.0ubuntu3
---------------
apt (3.1.0ubuntu3) questing; urgency=medium
* solver3: Only merge dependencies on the same package
-- Julian Andres Klode <juli...@ubuntu.com> Wed, 28 May 2025 14:34:31
+0200
** Changed in: apt (Ubuntu Questing)
Status: Fix Committed => Fix Released
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https://bugs.launchpad.net/bugs/2111742
Title:
3.0 solver inadvertently removes packages during install
Status in apt package in Ubuntu:
Fix Released
Status in apt source package in Plucky:
Triaged
Status in apt source package in Questing:
Fix Released
Bug description:
[Impact]
The solver evaluation revealed cases where installing new packages
inadvertently removed manually installed packages from the system such as
ubuntu-minimal.
For users on the default solver, this causes two issues:
1. If the default solver fails to find a solution, it may fall back to
the new solver and present the inadvertent solution.
2. If the solution is not presented, but worse, and a report filed
with errors.ubuntu.com
For users using the 3.0 solver explicitly, for example, using the
`--solver 3.0` argument or setting `APT::Solver "3.0"` in apt.conf,
the issue only has an effect if the option `APT::Solver::RemoveManual`
is set to `1`, which is not the default case.
[Test plan]
Replay the APT solver dump
https://errors.ubuntu.com/oops/1b55173a-3526-11f0-b7ac-fa163e171f02
https://errors.ubuntu.com/oops/dbd5149e-36b9-11f0-bb74-fa163ec44ecd
And ensure that no manual package is being removed.
To replay the solver dump:
Pass the AptSolverDump value through
base64 -d | zstd -d | /usr/lib/apt/solvers/solver3 -o
APT::Solver::RemoveManual=1
and ensure that the problem can be resolved without removing any
packages, that is,
1. The output ends with Message: Done
2. The output contains no Remove: lines
To further analyse the output the analyse-edsp.py tool from the edsp test
suite may be helpful:
https://salsa.debian.org/apt-team/apt-tests/-/tree/main?ref_type=heads
[Where problems could occur]
Problems could occur for users who manually use `--solver 3.0` if the new
assumption mechanism or the changes to enable it contain errors - it may
fail to find a solution where it did before, for example.
For default users, this may cause additional slow downs or reports to
be generated for cases where no reports where previously generated (or
in the worst case apt segfaulting).
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/apt/+bug/2111742/+subscriptions
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