package grub-efi-amd64-signed 1.142.4+2.04-1ubunt2 failed to install/upgrade: installed grub-efi-amd64-signed package post-installation script subprocess returned error exit status 1

[Nicolas Becker]

When upgrading from 19.04 to 20.04, the installer crash when upgrading Grub and made the system unbootable. I had to boot on a live disk and reistall using boot-repair (thank you to these guys).

ProblemType: Package
DistroRelease: Ubuntu 20.04
Package: grub-efi-amd64-signed 1.142.4+2.04-1ubuntu26.2
ProcVersionSignature: Ubuntu 5.4.0-42.46-generic 5.4.44
Uname: Linux 5.4.0-42-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.4
Architecture: amd64
CasperMD5CheckResult: skip
Date: Wed Jul 29 10:07:58 2020
ErrorMessage: installed grub-efi-amd64-signed package post-installation script subprocess returned error exit status 1
InstallationDate: Installed on 2019-10-19 (287 days ago)
InstallationMedia: Ubuntu 18.04.3 LTS "Bionic Beaver" - Release amd64 (20190805)
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 2.0.2ubuntu0.1
SourcePackage: grub2-signed
Title: package grub-efi-amd64-signed 1.142.4+2.04-1ubuntu26.2 failed to install/upgrade: installed grub-efi-amd64-signed package post-installation script subprocess returned error exit status 1
UpgradeStatus: Upgraded to focal on 2020-07-29 (4 days ago)

[Launchpad Janitor (janitor)]

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

[crysman (crysman)]

This has occured just now, no upgrade from previous Ubuntu, this is a fresh install, have not rebooted yet.