20.02 LTS upgrade fails with package imagemagick-6-common 8:6.9.10.23+dfsg-2.1ubuntu11 failed to install/upgrade: conffile difference visualizer subprocess returned error exit status 127

[magor]

I ran do-release-upgrade -d on a development server.
I had to install the old imagemagick 6 libs to hack-around issues in the version 7.

ProblemType: Package
DistroRelease: Ubuntu 20.04
Package: imagemagick-6-common 8:6.9.10.23+dfsg-2.1ubuntu11
ProcVersionSignature: Ubuntu 4.15.0-99.100-generic 4.15.18
Uname: Linux 4.15.0-99-generic x86_64
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
CasperMD5CheckResult: skip
Date: Tue May 5 15:45:29 2020
Dependencies:

ErrorMessage: conffile difference visualizer subprocess returned error exit status 127
InstallationDate: Installed on 2017-03-18 (1143 days ago)
InstallationMedia: Ubuntu-Server 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
PackageArchitecture: all
Python3Details: /usr/bin/python3.8, Python 3.8.2, python3-minimal, 3.8.2-0ubuntu2
PythonDetails: /usr/bin/python2.7, Python 2.7.18rc1, python-is-python2, 2.7.17-4
RelatedPackageVersions:
 dpkg 1.19.7ubuntu3
 apt 2.0.2
SourcePackage: imagemagick
Title: package imagemagick-6-common 8:6.9.10.23+dfsg-2.1ubuntu11 failed to install/upgrade: conffile difference visualizer subprocess returned error exit status 127
UpgradeStatus: Upgraded to focal on 2020-05-05 (0 days ago)
modified.conffile..etc.ImageMagick-6.type-urw-base35.xml: [deleted]
mtime.conffile..etc.ImageMagick-6.policy.xml: 2018-10-09T10:18:01.399661

[Launchpad Janitor (janitor)]

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