vanilla-gnome-default-settings will not install for impish-proposed

[Paul Broadhead]

Impact
------
A user that tries to install vanilla-gnome-default-settings (or its reverse dependency vanilla-gnome-desktop) gets an error every time they use apt. There isn't a built in way in apt to fix this error.

Test Case
---------
Enabled proposed updates
From a terminal, run
sudo apt install vanilla-gnome-default-settings
The install should complete without any dpkg errors.

Also, test uninstalling.
sudo apt remove vanilla-gnome-default-settings
The removal should complete without any dpkg errors.

(And then install again if you want it installed.)

Where Problems Could Occur
--------------------------
This is a two-line typo fix. It's not really possible to make this worse since the current package already leaves dpkg in a very unhappy state.

Original Bug Report
-------------------
Keen to try out Gnome 40 on impish, I enabled impish-proposed and updated, all was fine. I prefer the upstream vanilla gnome experience so installed vanilla-gnome-desktop which depends on vanilla-gnome-default-settings. However, vanilla-gnome-default-settings installation failed:

Setting up vanilla-gnome-default-settings (20.04.1) ...
update-alternatives: error: no alternatives for gdm3-theme.gresource
dpkg: error processing package vanilla-gnome-default-settings (--configure):
 installed vanilla-gnome-default-settings package post-installation script subprocess returned error exit status 2
Errors were encountered while processing:
 vanilla-gnome-default-settings
E: Sub-process /usr/bin/dpkg returned an error code (1)

1) $ lsb_release -rd
Description: Ubuntu Impish Indri (development branch)
Release: 21.10

2) $ apt-cache policy vanilla-gnome-default-settings
vanilla-gnome-default-settings:
  Installed: 20.04.1
  Candidate: 20.04.1
  Version table:
 *** 20.04.1 500
        500 http://gb.archive.ubuntu.com/ubuntu impish/universe amd64 Packages
        500 http://gb.archive.ubuntu.com/ubuntu impish/universe i386 Packages
        100 /var/lib/dpkg/status

3) I would expect the package to install without errors.

4) Instead it does not complete installation.

Further attempts to --configure etc also fail.

I understand this is software in development, I'm just trying to help. Thanks for all your hard work.

[Launchpad Janitor (janitor)]

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

[Paul White (paulw2u)]

I'm adding a 'me too' as my impish installation included the 'vanilla-gnome-desktop' package before the update to GNOME 40 occurred. For reasons not relevant here, any attempt to remove that package resulted in dpkg output that referred to there being too many errors.

It seems that the package cannot currently be installed but if already installed, before various updates applied, cannot be removed.

[Paul Broadhead (pjbroad)]

I have a manual fix for this.

Edit "/var/lib/dpkg/info/vanilla-gnome-default-settings.postinst"

Change "gdm3-theme.gresource" to "gdm-theme.gresource"

Then "sudo apt install -f"

The vanilla gnome setup now works as expected.

[Paul Broadhead (pjbroad)]

Patch attached

[Rick Gatewood (george-gatewood)]

Thanks for this fix!

[seanh (seanh)]

Same issue here with the released version of Impish. Paul Broadhead's patch seemed to work for me

[Edison Wong (hswong3i)]

Confirm https://launchpadlibrarian.net/558591298/ubuntu-gnome-default-settings-patch-bug-1935767 solve the issue. Thank you very much.

[Henri Menke (hmenke)]

Adding a "me too" for jammy and confirming that the proposed fix resolves the issue. Please address this as soon as possible, otherwise vanilla-gnome-desktop will not be installable in the next LTS release.

[Jeremy Bícha (jbicha)]

This is fixed for Ubuntu 22.04 LTS with
https://launchpad.net/ubuntu/+source/ubuntu-gnome-default-settings/22.04.1
I forgot to include the bug number in that upload.

[Launchpad Janitor (janitor)]

This bug was fixed in the package ubuntu-gnome-default-settings - 22.04.2

---------------
ubuntu-gnome-default-settings (22.04.2) jammy; urgency=medium

  * Also fix the prerm script for GDM's gresource file (LP: #1935767)

 -- Jeremy Bicha <email address hidden> Fri, 11 Feb 2022 17:43:38 -0500

[Paul Broadhead (pjbroad)]

Thanks for the fix, I can confirm the update for Jammy installed without errors and "apt purge" and "apt install" on the package worked too.

Will you be back porting the fix to impish?

[Jeremy Bícha (jbicha)]

> Will you be back porting the fix to impish?

Yes

[Edison Wong (hswong3i)]

>> Will you be back porting the fix to impish?

> Yes

May I double confirm if we are going to back porting the fix to impish? I am testing it again on today (2022-06-07) but fix seems still didn't applied?

[Edison Wong (hswong3i)]

It looks a bit silly for waiting a single line of patch being applied to a Ubuntu point release which going to be EOL on 2022-07-14... So I simply make my hand dirty with OBS as below (patch applied):

  * https://build.opensuse.org/package/show/home:alvistack/ubuntu-gnome-default-settings-20.04.1
  * https://download.opensuse.org/repositories/home:/alvistack/xUbuntu_21.10/all/vanilla-gnome-default-settings_20.04.1_all.deb

To whom also need this patch for impish (now, not after 2022-07-14...), you could try in this way:

    apt-get update
    apt-get install -y wget
    wget https://download.opensuse.org/repositories/home:/alvistack/xUbuntu_21.10/all/vanilla-gnome-default-settings_20.04.1_all.deb
    dpkg -i vanilla-gnome-default-settings_20.04.1_all.deb
    apt-get install -y vanilla-gnome-desktop

[Brian Murray (brian-murray)]

Ubuntu 21.10 (Impish Indri) has reached end of life, so this bug will not be fixed for that specific release.