package grub-pc 2.04-1ubuntu26.4 failed to install/upgrade: installed grub-pc package post-installation script subprocess returned error exit status 1

[Paul Webb]

I had to power cycle my server and it shows that I am running Ubuntu 20.04.1 LTS now

ProblemType: Package
DistroRelease: Ubuntu 20.04
Package: grub-pc 2.04-1ubuntu26.4
ProcVersionSignature: Ubuntu 4.15.0-122.124-generic 4.15.18
Uname: Linux 4.15.0-122-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.10
Architecture: amd64
CasperMD5CheckResult: skip
Date: Thu Oct 22 20:36:30 2020
DuplicateSignature:
 package:grub-pc:2.04-1ubuntu26.4
 Setting up grub-pc (2.04-1ubuntu26.4) ...
 dpkg: error processing package grub-pc (--configure):
  installed grub-pc package post-installation script subprocess returned error exit status 1
ErrorMessage: installed grub-pc package post-installation script subprocess returned error exit status 1
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-122-generic root=UUID=4f8b85db-8c11-422b-83c4-c74195f67b91 ro console=tty1 root=LABEL=DOROOT notsc clocksource=kvm-clock net.ifnames=0
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: grub2
Title: package grub-pc 2.04-1ubuntu26.4 failed to install/upgrade: installed grub-pc package post-installation script subprocess returned error exit status 1
UpgradeStatus: Upgraded to focal on 2020-10-22 (0 days ago)

[Launchpad Janitor (janitor)]

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

[Julian Andres Klode (juliank)]

Well, you did upgrade from 18.04 to 20.04, but that's irrelevant to this bug report, which is a duplicate of bug 1896608. But how can you be surprised about having upgraded after an upgrade?