ubuntu-release-upgrader crashed with apt_pkg.Error: E:can not open /var/lib/apt/lists/in.archive.ubuntu.com_ubuntu_dists_bionic_InRelease - fopen (13: Permission denied), E:The package lists or status file could not be parsed or opened.

[errors.ubuntu.com bug bridge]

The Ubuntu Error Tracker has been receiving reports about a problem regarding ubuntu-release-upgrader. This problem was most recently seen with package version 1:20.10.16, the problem page at https://errors.ubuntu.com/problem/31fbeeb9c2355df96a76732a48d29d35851ada3d contains more details, including versions of packages affected, stacktrace or traceback, and individual crash reports.
If you do not have access to the Ubuntu Error Tracker and are a software developer, you can request it at http://forms.canonical.com/reports/.

[Brian Murray (brian-murray)]

The Traceback follows:

Traceback (most recent call last):
  File "/usr/lib/ubuntu-release-upgrader/check-new-release-gtk", line 192, in <module>
    cnr = CheckNewReleaseGtk(options)
  File "/usr/lib/ubuntu-release-upgrader/check-new-release-gtk", line 78, in __init__
    m = MetaRelease(useDevelopmentRelease=options.devel_release,
  File "/usr/lib/python3/dist-packages/UpdateManager/MetaReleaseGObject.py", line 44, in __init__
    MetaReleaseCore.__init__(self, useDevelopmentRelease, useProposed)
  File "/usr/lib/python3/dist-packages/UpdateManager/Core/MetaRelease.py", line 100, in __init__
    cache = apt.Cache()
  File "/usr/lib/python3/dist-packages/apt/cache.py", line 152, in __init__
    self.open(progress)
  File "/usr/lib/python3/dist-packages/apt/cache.py", line 214, in open
    self._cache = apt_pkg.Cache(progress)
apt_pkg.Error: E:can not open /var/lib/apt/lists/in.archive.ubuntu.com_ubuntu_dists_bionic_InRelease - fopen (13: Permission denied), E:The package lists or status file could not be parsed or opened.

[Brian Murray (brian-murray)]

I was able to recreate this my using "chmod o-r /var/lib/apt/lists/*". Is this a configuration issue on the system or should apt cache only be used by root?