Undefined XML entity in about:preferences: <preftab id="MailPreferences" flex="1"

[Olivier Tilloy]

With thunderbird 78.2.1 from groovy-proposed, when I open the preferences from the hamburger menu, I get an error page in a new tab, complaining about an undefined XML entity. See attached screenshot.

ProblemType: Bug
DistroRelease: Ubuntu 20.10
Package: thunderbird 1:78.2.1+build1-0ubuntu1
ProcVersionSignature: Ubuntu 5.8.0-18.19-generic 5.8.4
Uname: Linux 5.8.0-18-generic x86_64
ApportVersion: 2.20.11-0ubuntu45
Architecture: amd64
BuildID: 20200828182639
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Wed Sep 9 16:51:51 2020
DefaultProfileExtensions: extensions.sqlite corrupt or missing
DefaultProfileIncompatibleExtensions: Unavailable (corrupt or non-existant compatibility.ini or extensions.sqlite)
DefaultProfileLocales: extensions.sqlite corrupt or missing
DefaultProfilePrefErrors: Unexpected character ',' before close parenthesis @ /usr/lib/thunderbird/omni.ja:greprefs.js:732
DefaultProfileThemes: extensions.sqlite corrupt or missing
InstallationDate: Installed on 2020-01-20 (232 days ago)
InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Alpha amd64 (20200117)
Profiles:
 Profile1 (Default) - LastVersion=None/None (Out of date)
 Profile0 - LastVersion=None/None (Out of date)
SourcePackage: thunderbird
UpgradeStatus: No upgrade log present (probably fresh install)

[Olivier Tilloy (osomon)]

When I use the error console, I'm seeing the same error about the undefined XML entity, and if I click on the corresponding link to view the source ("preferences:40:1"), I then get another window with another undefined XML entity error:

  Location: chrome://messenger/content/viewSource.xul
  Line 62, Column 5:

    <key id="key_undo" key="&undoCmd.key;" modifiers="accel" command="cmd_undo"/>
----^

[Olivier Tilloy (osomon)]

Upstream builds don't appear to be affected, so it's an Ubuntu-specific bug.

[Olivier Tilloy (osomon)]

thunderbird 1:78.2.1+build1-0ubuntu1 is now in the release pocket, and I can't reproduce the bug any longer. Closing.