FFe [Ubuntu 18.04] Error installing the "Basic Ubuntu Server"

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When selecting the "Basic Ubuntu Server" from the installation dialogs of the daily-build ISO 390 images, the following error message is displayed:

     Installation step failed
     An installation step failed. You can try to run the failing item again from the menu,
     or skip it and choose something else. The failing step is: Select and install software

At the time of the error, the /var/log/syslog file of the installer system showed the following entries:

Mar 22 08:21:03 in-target: The following information may help to resolve the situation:
Mar 22 08:21:03 in-target:
Mar 22 08:21:03 in-target: The following packages have unmet dependencies:
Mar 22 08:21:03 in-target: python3-cryptography : Depends: python3-cffi-backend-api-min (<= 9729) but it is not installable
Mar 22 08:21:03 in-target: Depends: python3-cffi-backend-api-max (>= 9729) but it is not installable
Mar 22 08:21:03 in-target: E
Mar 22 08:21:03 in-target: :
Mar 22 08:21:03 in-target: Unable to correct problems, you have held broken packages.
Mar 22 08:21:03 in-target:
Mar 22 08:21:03 in-target: tasksel: apt-get failed (100)
Mar 22 08:21:04 main-menu[366]: WARNING **: Configuring 'pkgsel' failed with error code 1
Mar 22 08:21:04 main-menu[366]: WARNING **: Menu item 'pkgsel' failed.

The problem occured when installing from the daily builds from 19. through 22. March 2018.

Installation logs/information from the /var/log/installer directory are attached.

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Default Comment by Bridge

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Steve Langasek (vorlon)]

The python3-cryptography package's dependencies are correct; both python3-cffi-backend-api-min (= 9729) and python3-cffi-backend-api-max (=10495) are provided by python3-cffi-backend 1.11.5-1, so the package is installable in the archive.

However, python3-cffi-backend has not been pulled into the package pool on the ISO, so an install without access to network apt sources is going to fail.

This is a bug in the CD mastering scripts, which probably don't understand versioned provides (a relatively recent feature of dpkg).

[Steve Langasek (vorlon)]

? Unknown dependency python3-cffi-backend-api-min (<= 9729) by python3-cryptography
? Unknown dependency python3-cffi-backend-api-max (>= 9729) by python3-cryptography

http://people.canonical.com/~ubuntu-archive/cd-build-logs/ubuntu-server/bionic/daily-20180322.log

The failure to resolve the versioned provides happens in germinate.

[Steve Langasek (vorlon)]

I have deployed a local workaround on the image build server to have germinate consider versioned provides, so a new daily image is now available that has the correct set of packages included in the package pool.

This could negatively impact other image flavors, in which case we might have to revert it again until proper germinate support for versioned provides can land. However, the risk to live images is comparatively small as there's very little of import in the package pools anyway.

[Colin Watson (cjwatson)]

I've implemented proper versioned Provides support in germinate, uploaded it to Debian unstable, and deployed it on pepo (ftpmaster) and nusakan (cdimage). Once Launchpad's Debian import picks up the change in unstable, I'll sync it to bionic which will close this bug.

[Colin Watson (cjwatson)]

https://git.launchpad.net/germinate/commit/?id=9382162df8ff0523c6ae0e64cd86f331a2603497

[Colin Watson (cjwatson)]

I guess this technically ought to be a feature freeze exception request. Subscribing ~ubuntu-release for that.

[Łukasz Zemczak (sil2100)]

FFe approved.

[Launchpad Janitor (janitor)]

This bug was fixed in the package germinate - 2.28

---------------
germinate (2.28) unstable; urgency=medium

  * Support versioned Provides (LP: #1758004).
  * Build-depend on dh-python.

 -- Colin Watson <email address hidden> Fri, 23 Mar 2018 11:18:15 +0000

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------- Comment From <email address hidden> 2018-03-27 11:39 EDT-------
IBM bugzilla closed -> Fix Release and verified