package sudo 1.9.9-1ubuntu2 failed to install/upgrade: installed sudo package post-installation script subprocess returned error exit status 1

[Dolf Schimmel (Freeaqingme)]

This error happened while running do-release-upgrade to yammy. I specifically indicated (iirc) that the /etc/sudoers file should not be touched.

Apparently something during the install did attempt to touch the file, and failed in doing so because it was marked as immutable.

ProblemType: Package
DistroRelease: Ubuntu 22.04
Package: sudo 1.9.9-1ubuntu2
ProcVersionSignature: Ubuntu 5.4.0-100.113-generic 5.4.166
Uname: Linux 5.4.0-100-generic x86_64
ApportVersion: 2.20.11-0ubuntu79
Architecture: amd64
CasperMD5CheckResult: pass
Date: Thu Mar 24 10:03:57 2022
DuplicateSignature:
 package:sudo:1.9.9-1ubuntu2
 Installing new version of config file /etc/sudoers.d/README ...
 chown: changing ownership of '/etc/sudoers': Operation not permitted
 dpkg: error processing package sudo (--configure):
  installed sudo package post-installation script subprocess returned error exit status 1
ErrorMessage: installed sudo package post-installation script subprocess returned error exit status 1
InstallationDate: Installed on 2022-02-08 (44 days ago)
InstallationMedia: Ubuntu-Server 20.04.3 LTS "Focal Fossa" - Release amd64 (20210824)
Python3Details: /usr/bin/python3.10, Python 3.10.3, python3-minimal, 3.10.1-0ubuntu2
PythonDetails: N/A
RebootRequiredPkgs: Error: path contained symlinks.
RelatedPackageVersions:
 dpkg 1.21.1ubuntu1
 apt 2.4.1
SourcePackage: sudo
Title: package sudo 1.9.9-1ubuntu2 failed to install/upgrade: installed sudo package post-installation script subprocess returned error exit status 1
UpgradeStatus: Upgraded to jammy on 2022-03-24 (0 days ago)
VisudoCheck:
 Error: command ['/usr/sbin/visudo', '-c'] failed with exit code 1: /etc/sudoers.d/ubuntu: bad permissions, should be mode 0440
 /etc/sudoers: parsed OK
 /etc/sudoers.d/90-cloud-init-users: parsed OK
 /etc/sudoers.d/README: parsed OK
mtime.conffile..etc.sudoers: 2022-03-16T10:50:27.520251