package grub-efi-amd64-signed 1.142.8+2.04-1ubuntu26.6 failed to install/upgrade: installed grub-efi-amd64-signed package post-installation script subprocess returned error exit status 32

[Christopher Taylor]

Prompted for upgrade on a my Ubuntu installation in Azure. Grub had issues identifying the correct drive to install to, even after I used the wizard to specify one.

ProblemType: Package
DistroRelease: Ubuntu 20.04
Package: grub-efi-amd64-signed 1.142.8+2.04-1ubuntu26.6
ProcVersionSignature: Ubuntu 5.4.0-1031.32~18.04.1-azure 5.4.65
Uname: Linux 5.4.0-1031-azure x86_64
ApportVersion: 2.20.11-0ubuntu27.12
Architecture: amd64
CasperMD5CheckResult: skip
Date: Sat Nov 14 10:56:00 2020
DuplicateSignature:
 package:grub-efi-amd64-signed:1.142.8+2.04-1ubuntu26.6
 Setting up grub-efi-amd64-signed (1.142.8+2.04-1ubuntu26.6) ...
 mount: /var/lib/grub/esp: /dev/sdb already mounted or mount point busy.
 dpkg: error processing package grub-efi-amd64-signed (--configure):
  installed grub-efi-amd64-signed package post-installation script subprocess returned error exit status 32
ErrorMessage: installed grub-efi-amd64-signed package post-installation script subprocess returned error exit status 32
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-signed
Title: package grub-efi-amd64-signed 1.142.8+2.04-1ubuntu26.6 failed to install/upgrade: installed grub-efi-amd64-signed package post-installation script subprocess returned error exit status 32
UpgradeStatus: Upgraded to focal on 2020-11-14 (0 days ago)