[Bug 1791931] Re: Update-manager crashes in _show_transaction due to packages being already removed

[Łukasz Zemczak]

Hello errors.ubuntu.com, or anyone else affected,

Accepted update-manager into xenial-proposed. The package will build now
and be available at https://launchpad.net/ubuntu/+source/update-
manager/1:16.04.14 in a few hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.  Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested and change the tag from
verification-needed-xenial to verification-done-xenial. If it does not
fix the bug for you, please add a comment stating that, and change the
tag to verification-failed-xenial. In either case, without details of
your testing we will not be able to proceed.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance for helping!

N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.

** Changed in: update-manager (Ubuntu Xenial)
       Status: New => Fix Committed

** Tags added: verification-needed-xenial

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https://bugs.launchpad.net/bugs/1791931

Title:
  Update-manager crashes in _show_transaction due to packages being
  already removed

Status in update-manager package in Ubuntu:
  Fix Released
Status in update-manager source package in Xenial:
  Fix Committed
Status in update-manager source package in Bionic:
  Fix Committed

Bug description:
  [Impact]

   * Update-manager crashes when it tries to remove a package that was
  already removed since update-manager refreshed its cache. A typical
  scenario is when the list of available packages is updated, then
  update-manager pops up to notify the user about the updates. The user
  is not in front of the screen and unattended-upgrades installs the
  security updates and removes unused kernels making the list of updates
  shown to the user outdated. User clicks "Install now" and update-
  manager crashes.

   * The fix obtains a fresh cache and skips package operations that
  would be obsolete and result an exception.

  [Test Case ]

   (with Bionic's package names)
   * Install older kernel packages, downgrade a few packages and mark the kernels autoremovable:
     $ sudo eatmydata apt install -y --allow-downgrades linux-headers-4.15.0-32 linux-headers-4.15.0-32-generic libpoppler73=0.62.0-2ubuntu2 poppler-utils=0.62.0-2ubuntu2 ; sudo /etc/kernel/postinst.d/apt-auto-removal ; sudo apt-mark auto linux-headers-4.15.0-32  linux-headers-4.15.0-32-generic

   * Start update-manager in a different terminal and _don't_ start the
  upgrade

   * Remove kernel packages behind u-m's back:
     $ sudo eatmydata apt remove -y linux-headers-4.15.0-32

   * Start the update on update-manager's GUI and observe it not
  crashing with the fixed version

  [Regression Potential]

   * Too eager filtering could let packages not updated/not removed, but the next run of update-manager would retry updating/removing them.
   * Obtaining a fresh cache takes a ~100 milliseconds and the GUI may freeze for that time. For this short time u-m could show itself busy but IMO it would be more disturbing than the potentially not noticeable freeze.

  [Original bug text]

  The Ubuntu Error Tracker has been receiving reports about a problem regarding update-manager.  This problem was most recently seen with package version 1:18.04.11.4, the problem page at https://errors.ubuntu.com/problem/c4f194c0df19fca32a25eff8c633ad69fe9b5abb contains more details, including versions of packages affected, stacktrace or traceback, and individual crash reports.
  If you do not have access to the Ubuntu Error Tracker and are a software developer, you can request it at http://forms.canonical.com/reports/.

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