update-manager crashed with AttributeError in _records(): 'NoneType' object has no attribute 'lookup'

[Steve Slagle]

System locked up

ProblemType: Crash
DistroRelease: Ubuntu 20.04
Package: update-manager 1:20.04.1
ProcVersionSignature: Ubuntu 5.4.0-21.25-generic 5.4.27
Uname: Linux 5.4.0-21-generic x86_64
ApportVersion: 2.20.11-0ubuntu24
Aptdaemon:

Architecture: amd64
CrashCounter: 1
CurrentDesktop: ubuntu:GNOME
Date: Tue Apr 7 09:16:14 2020
ExecutablePath: /usr/bin/update-manager
InstallationDate: Installed on 2020-03-01 (36 days ago)
InstallationMedia: Ubuntu 19.10 "Eoan Ermine" - Release amd64 (20191017)
InterpreterPath: /usr/bin/python3.8
PackageArchitecture: all
ProcCmdline: /usr/bin/python3 /usr/bin/update-manager --no-update --no-focus-on-map
ProcEnviron:
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
Python3Details: /usr/bin/python3.8, Python 3.8.2, python3-minimal, 3.8.2-0ubuntu2
PythonArgs: ['/usr/bin/update-manager', '--no-update', '--no-focus-on-map']
PythonDetails: N/A
SourcePackage: update-manager
Title: update-manager crashed with AttributeError in _records(): 'NoneType' object has no attribute 'lookup'
UpgradeStatus: Upgraded to focal on 2020-03-25 (12 days ago)
UserGroups: adm cdrom dip lpadmin lxd plugdev sambashare sudo

[Launchpad Janitor (janitor)]

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

[Steve Langasek (vorlon)]

The stacktrace points to:

  File "/usr/lib/python3/dist-packages/apt/package.py", line 541, in _records
    if not self.package._pcache._records.lookup(self._cand.file_list[0]):
AttributeError: 'NoneType' object has no attribute 'lookup'

So, reassigning.

[Steve Langasek (vorlon)]

And the bug report shows this crash happened with python3-apt 1.9.10, which was a prerelease version of python3-apt before Ubuntu 20.04 LTS came out. So I'm surprised another user has just marked this bug as affecting them, causing the report to bubble up to the top. We would need some concrete evidence that this failure happens with released versions of the software to take further action here.

[Launchpad Janitor (janitor)]

[Expired for python-apt (Ubuntu) because there has been no activity for 60 days.]