[Bug 2034986] Re: some text became unreadable during a distribution upgrade

Sat Oct 14 14:20:35 UTC 2023

Since I propose yet another SRU, I created bug #2039356. This bug report
is quite noisy already...

My examination of the flavors with respect to this issue focused on two
questions:

1. Does the u-r-u model effectively prevent 'the unreadable text issue'
when the desktop font in use — whether default or set by the user — has
changed during the cycle?

After the changes proposed via bug #2039356 I would say "yes" for:

 Ubuntu Desktop
 Ubunu Budgie
 Ubuntu Cinnamon
 Ubuntu Kylin
 Ubuntu MATE
 Ubuntu Unity

while the model (i.e. temporarily changing a dconf value which
represents the desktop font) is not effective for:

 Kubuntu
 Lubuntu
 Xubuntu

In case of Kubuntu and Lubuntu the Qt way of dealing with fonts seems to
require something else, and the Xfce way applied in Xubuntu means
similar difficulties. Fortunately all those flavors use a desktop font
by default (Noto Sans) which was not changed during the cycle, so this
does not need to be addressed for mantic.

But if you like, you can trigger the 23.04 -> 23.10 upgrade issue in for
instance Xubuntu: Go to Settings -> Appearance -> Fonts and change the
"Default Font" from Noto Sans to Ubuntu. Doing so will be reflected both
in the ~/.config/xfce4/xfconf/xfce-perchannel-xml/xsettings.xml file and
in dconf (gsettings get org.gnome.desktop.interface font-name), but
changing the font-name dconf value only to something else during upgrade
(as we do) won't change the effective desktop font in Xubuntu, which
results in 'the unreadable text issue'.

2. Is the temporary desktop font dconf value properly reset at next
login after reboot?

Yes it is, after the changes proposed via bug #2039356.

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https://bugs.launchpad.net/bugs/2034986

Title:
  some text became unreadable during a distribution upgrade

Status in Cinnamon:
  New
Status in Ubuntu MATE:
  New
Status in ubuntu-meta package in Ubuntu:
  Fix Released
Status in ubuntu-release-upgrader package in Ubuntu:
  Fix Committed
Status in ubuntu-release-upgrader source package in Jammy:
  Fix Committed
Status in ubuntu-release-upgrader source package in Lunar:
  Fix Committed
Status in ubuntu-meta source package in Mantic:
  Fix Released
Status in ubuntu-release-upgrader source package in Mantic:
  Fix Committed

Bug description:
  [ Impact ]

   * On Ubuntu Mate with the Lunar series, when running
     ubuntu-release-upgrader, the displayed font of running
     applications (including the upgrader) becomes very corrupted.

   * This is not just a display problem, it is also a functional one.
     The release upgrader will have text corrupted to the point
     where a dialog asks a decision, and displays two buttons, but the
     text is unreadable and one has to guess which button is the one
     that carries out their desired action.

   * In the early parts of the upgrader tool, users are told in bold:
     "To prevent data loss close all open applications and documents."
     This is just before the "Start Upgrade" button is available.
     But they may not do so.  Many applications may have a corrupted
     font.

   * To address this, an additional environment variable is being
     passed along to pkexec, XDG_CURRENT_DESKTOP, as this is the
     critical criteria for making the Mate version of the fix work.

   * Also in the change are
     * an update to tests
     * from pre-build.sh
       * an update of the mirrors.cfg, adding and removing several
         mirrors
       * a refresh of the po files

  [ Test Plan ]

   * acquire an Ubuntu Mate environment running Ubuntu Lunar on amd64

   * as user, run "update-manager -d"

   * monitor the "Distribution Upgrade" screen.  During the "Installing
     the upgrades" step (and mind that this step will be long), observe
     the text of the "Distribution Upgrade" screen and verify that the
     font does not corrupt.

   * Repeat the above for Ubuntu Desktop

  [ Where problems could occur ]

   * We are changing, at release time, ubuntu-release upgrader.  If we
     are careless, we could regress upgrades for a wider group of users
     than just Ubuntu Mate.  That said, it is believed that passing the
     additional XDG_CURRENT_DESKTOP variable is relatively low risk.

  [ Other Info ]

   * TBD

  ---

  Original description:

  I was upgrading from Lunar to Mantic the other day and left a couple
  of applications open during the upgrade process. During the upgrade
  the text in audacious became unreadable (I'll attach a screenshot) and
  I seem to recall the title bar of Firefox being unreadable but the
  contents of web pages still being readable.

  ProblemType: Bug
  DistroRelease: Ubuntu 23.10
  Package: ubuntu-release-upgrader-core 1:23.10.5
  ProcVersionSignature: Ubuntu 6.5.0-4.4-generic 6.5.0
  Uname: Linux 6.5.0-4-generic x86_64
  NonfreeKernelModules: nvidia_modeset nvidia zfs
  ApportVersion: 2.27.0-0ubuntu2
  Architecture: amd64
  CasperMD5CheckResult: unknown
  CrashDB: ubuntu
  CurrentDesktop: ubuntu:GNOME
  Date: Fri Sep  8 15:39:27 2023
  InstallationDate: Installed on 2018-08-10 (1855 days ago)
  InstallationMedia: Ubuntu-Server 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
  PackageArchitecture: all
  SourcePackage: ubuntu-release-upgrader
  Symptom: ubuntu-release-upgrader
  UpgradeStatus: Upgraded to mantic on 2023-09-06 (2 days ago)
  VarLogDistupgradeAptclonesystemstate.tar.gz: Error: command ['pkexec', 'cat', '/var/log/dist-upgrade/apt-clone_system_state.tar.gz'] failed with exit code 126: Error executing command as another user: Request dismissed
  VarLogDistupgradeTermlog:

  mtime.conffile..etc.update-manager.meta-release:
  2021-05-27T16:30:16.970490

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