package openjdk-14-jre-headless:amd64 14.0.2+12-1~20.04 failed to install/upgrade: installed openjdk-14-jre-headless:amd64 package post-installation script subprocess returned error exit status 2

[Stefan Strömer]

Reported this quite a few times.
Seems post installation scripts cannot be started or are not present.
It's annoying, because every time 'apt update' or 'apt upgrade' is started this problem is reported.

ProblemType: Package
DistroRelease: Ubuntu 20.04
Package: openjdk-14-jre-headless:amd64 14.0.2+12-1~20.04
ProcVersionSignature: Ubuntu 5.4.0-47.51-generic 5.4.55
Uname: Linux 5.4.0-47-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.13
Architecture: amd64
CasperMD5CheckResult: skip
Date: Sat Dec 5 14:44:52 2020
DuplicateSignature:
 package:openjdk-14-jre-headless:amd64:14.0.2+12-1~20.04
 Setting up openjdk-14-jre-headless:amd64 (14.0.2+12-1~20.04) ...
 update-alternatives: error: alternative keytool can't be master: it is a slave of jar
 dpkg: error processing package openjdk-14-jre-headless:amd64 (--configure):
  installed openjdk-14-jre-headless:amd64 package post-installation script subprocess returned error exit status 2
ErrorMessage: installed openjdk-14-jre-headless:amd64 package post-installation script subprocess returned error exit status 2
InstallationDate: Installed on 2017-09-11 (1180 days ago)
InstallationMedia: Ubuntu 17.04 "Zesty Zapus" - Release amd64 (20170412)
Python3Details: /usr/bin/python3.8, Python 3.8.5, python3-minimal, 3.8.2-0ubuntu2
PythonDetails: /usr/bin/python2.7, Python 2.7.18, python-is-python2, 2.7.17-4
RelatedPackageVersions:
 dpkg 1.19.7ubuntu3
 apt 2.0.2ubuntu0.1
SourcePackage: openjdk-14
Title: package openjdk-14-jre-headless:amd64 14.0.2+12-1~20.04 failed to install/upgrade: installed openjdk-14-jre-headless:amd64 package post-installation script subprocess returned error exit status 2
UpgradeStatus: Upgraded to focal on 2020-08-12 (114 days ago)