package grub-pc 2.02-2ubuntu8.4 failed to install/upgrade: installed grub-pc package post-installation script subprocess returned error exit status 1

[chuck more]

during upgrade from 17.1 to 18.04

ProblemType: Package
DistroRelease: Ubuntu 18.04
Package: grub-pc 2.02-2ubuntu8.4
ProcVersionSignature: Ubuntu 4.13.0-38.43-generic 4.13.16
Uname: Linux 4.13.0-38-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.3
Architecture: amd64
Date: Sat Sep 15 08:25:30 2018
ErrorMessage: installed grub-pc package post-installation script subprocess returned error exit status 1
InstallationDate: Installed on 2016-04-27 (870 days ago)
InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.13.0-38-generic root=UUID=1460eebd-9f34-429a-aec0-65c5fcb1593b ro quiet splash vt.handoff=7
Python3Details: /usr/bin/python3.6, Python 3.6.5, python3-minimal, 3.6.5-3ubuntu1
PythonDetails: /usr/bin/python2.7, Python 2.7.15rc1, python-minimal, 2.7.15~rc1-1
RelatedPackageVersions:
 dpkg 1.19.0.5ubuntu2
 apt 1.6.3ubuntu0.1
SourcePackage: grub2
Title: package grub-pc 2.02-2ubuntu8.4 failed to install/upgrade: installed grub-pc package post-installation script subprocess returned error exit status 1
UpgradeStatus: Upgraded to bionic on 2018-09-15 (0 days ago)

[Launchpad Janitor (janitor)]

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