package grub-pc 2.04-1ubuntu12.2 failed to install/upgrade: installed grub-pc package post-installation script subprocess returned error exit status 1

[Rovanion]

This happened during upgrade from 18.04 to 20.04.

ProblemType: Package
DistroRelease: Ubuntu 19.10
Package: grub-pc 2.04-1ubuntu12.2
ProcVersionSignature: Ubuntu 4.15.0-101.102-generic 4.15.18
Uname: Linux 4.15.0-101-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu8.9
Architecture: amd64
Date: Sat Jun 6 17:04:56 2020
ErrorMessage: installed grub-pc package post-installation script subprocess returned error exit status 1
InstallationDate: Installed on 2012-03-07 (3013 days ago)
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Beta amd64 (20120301)
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-101-generic root=UUID=34bcf296-c31f-410e-bad6-d299a2b74413 ro acpi_enforce_resources=lax quiet nomdmonddf nomdmonisw nomdmonddf nomdmonisw nomdmonddf nomdmonisw
Python3Details: /usr/bin/python3.7, Python 3.7.5, python3-minimal, 3.7.5-1
PythonDetails: /usr/bin/python2.7, Python 2.7.17, python-minimal, 2.7.17-1
RelatedPackageVersions:
 dpkg 1.19.7ubuntu2
 apt 1.9.4ubuntu0.1
SourcePackage: grub2
Title: package grub-pc 2.04-1ubuntu12.2 failed to install/upgrade: installed grub-pc package post-installation script subprocess returned error exit status 1
UpgradeStatus: Upgraded to eoan on 2020-06-06 (0 days ago)

[Rovanion (rovanion-luckey)]

Turns out I wasn't upgrading to 20.04 but 19.01. This bug is probably a duplicate of another bug I saw when reporting.

[Launchpad Janitor (janitor)]

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

[robert Newton (newtonsys-o)]

i upgraded from disco to focal by changing that word in /etc/apt/sources ;-)