[Bug 1317164] Re: Show reason of TransactionFailed and let the user try again instead of crashing

[Łukasz Zemczak]

Hello Brian, 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/1317164

Title:
  Show reason of TransactionFailed and let the user try again instead of
  crashing

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  shown to the user outdated.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 shows the reason of the transaction failure then asks
  offers the user to try again.

  [Test Case ]
   (with Bionic's package names)

   * Revert the patch for LP: #1791931 since it shadows the issue by
  filtering the package operations in advance.

   * 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 but showing the reason of the update
  failing and offering trying it again.

  [Regression Potential]

   * Inaccurate exception handling could shadow other problems.

  [Original bug text]

  On errors.ubuntu.com there are multiple crashes reported about update-
  manager that end in a Traceback like the following:

  aptdaemon.errors.TransactionFailed: Transaction failed: The package system is broken
   The following packages have unmet dependencies:

  rhythmbox-plugin-magnatune: Depends: rhythmbox (= 3.0.2-0ubuntu2) but
  3.0.2-0ubuntu1 is installed

  Naturally, the package name varies. I don't believe these are actually
  crashes about update-manager or aptdaemon. Rather there is something
  wrong with the users package system. Subsequently, it'd be better if
  these were not reported to the error tracker and clogging up the bug
  lists.

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