Stops with report "XML Parsing Error: undefined entity"

[ChrisOfBristol]

Ubuntu 20.10 - see apport file for details.

Starting Thunderbird (startup applications) causes this popup panel:

XML Parsing Error: undefined entity
Location: chrome://messenger/content/messenger.xhtml
Line Number 905, Column 3:
  <key id="openLightningKey"
--^

After closing the panel Thuderbird does not start. Unusable.

ProblemType: Bug
DistroRelease: Ubuntu 20.10
Package: thunderbird 1:78.3.2+build1-0ubuntu1
ProcVersionSignature: Ubuntu 5.8.0-26.27-generic 5.8.14
Uname: Linux 5.8.0-26-generic x86_64
AddonCompatCheckDisabled: False
ApportVersion: 2.20.11-0ubuntu50
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: chris 1396 F.... pulseaudio
 /dev/snd/controlC1: chris 1396 F.... pulseaudio
BuildID: 20201006011220
CasperMD5CheckResult: skip
Channel: Unavailable
CurrentDesktop: Budgie:GNOME
Date: Wed Oct 28 13:02:08 2020
ForcedLayersAccel: False
IncompatibleExtensions:
 English (GB) Language Pack - <email address hidden>
 Thunderbird (default) - {972ce4c6-7e08-4474-a285-3208198ce6fd}
InstallationDate: Installed on 2020-10-22 (5 days ago)
InstallationMedia: Ubuntu-Budgie 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731)
IpRoute:
 default via 192.168.0.1 dev wlx000f023f82a3 proto dhcp metric 600
 169.254.0.0/16 dev wlx000f023f82a3 scope link metric 1000
 192.168.0.0/24 dev wlx000f023f82a3 proto kernel scope link src 192.168.0.16 metric 600
MostRecentCrashID: bp-42ce8ef9-9373-4bdf-9fe7-26a6b0180227
PrefErrors: Unexpected character ',' before close parenthesis @ /usr/lib/thunderbird/omni.ja:greprefs.js:732
PrefSources: prefs.js
Profiles: Profile0 (Default) - LastVersion=78.3.2/20201006011220 (In use)
RunningIncompatibleAddons: True
SourcePackage: thunderbird
UpgradeStatus: Upgraded to groovy on 2020-10-23 (4 days ago)
dmi.bios.date: 05/30/2006
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A05
dmi.board.name: 0FJ030
dmi.board.vendor: Dell Inc.
dmi.chassis.type: 7
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvrA05:bd05/30/2006:svnDellInc.:pnDellDXP051:pvr:rvnDellInc.:rn0FJ030:rvr:cvnDellInc.:ct7:cvr:
dmi.product.name: Dell DXP051
dmi.sys.vendor: Dell Inc.
modified.conffile..etc.default.apport:
 # set this to 0 to disable apport, or to 1 to enable it
 # you can temporarily override this with
 # sudo service apport start force_start=1
 enabled=0
mtime.conffile..etc.default.apport: 2020-10-23T00:38:43.203925

[ChrisOfBristol (chrisofbristol-deactivatedaccount)]

Thank apport for creating a duplicate without checking for similar reports.