package grub-pc 2.04-1ubuntu26.9 failed to install/upgrade: installed grub-pc package post-installation script subprocess returned error exit status 127

[Rodolfo Ricci]

it's impossible tu update software and core Ubuntu

ProblemType: Package
DistroRelease: Ubuntu 20.04
Package: grub-pc 2.04-1ubuntu26.9
ProcVersionSignature: Ubuntu 5.4.0-52.57-generic 5.4.65
Uname: Linux 5.4.0-52-generic x86_64
NonfreeKernelModules: lkp_Ubuntu_5_4_0_52_57_generic_75 lkp_Ubuntu_5_4_0_52_57_generic_74
ApportVersion: 2.20.11-0ubuntu27.16
Architecture: amd64
CasperMD5CheckResult: skip
Date: Sun Apr 25 14:11:17 2021
DuplicateSignature:
 package:grub-pc:2.04-1ubuntu26.9
 Setting up grub-pc (2.04-1ubuntu26.9) ...
 /var/lib/dpkg/info/grub-pc.config: 1: /etc/default/grub: If: not found
 dpkg: error processing package grub-pc (--configure):
  installed grub-pc package post-installation script subprocess returned error exit status 127
ErrorMessage: installed grub-pc package post-installation script subprocess returned error exit status 127
InstallationDate: Installed on 2020-10-30 (176 days ago)
InstallationMedia: Ubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731)
InvalidGrubScript: /etc/default/grub
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.4.0-52-generic root=UUID=08468aab-b7d5-4159-b8c0-a43f5c4aaae1 ro i8042.reset quiet splash vt.handoff=7
Python3Details: /usr/bin/python3.8, Python 3.8.5, python3-minimal, 3.8.2-0ubuntu2
PythonDetails: N/A
RelatedPackageVersions:
 dpkg 1.19.7ubuntu3
 apt 2.0.5
SourcePackage: grub2
Title: package grub-pc 2.04-1ubuntu26.9 failed to install/upgrade: installed grub-pc package post-installation script subprocess returned error exit status 127
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

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

[Prasas Chabuk (pchabuk)]

/usr/sbin/grub-mkconfig: 10: /etc/default/grub: acpi: not found
run-parts: /etc/kernel/postrm.d/zz-update-grub exited with return code 127
dpkg: error processing package linux-image-5.4.0-26-generic (--remove):
 installed linux-image-5.4.0-26-generic package post-removal script subprocess returned error exit status 1
dpkg: too many errors, stopping
Errors were encountered while processing:
 linux-image-5.4.0-26-generic
Processing was halted because there were too many errors.

[Julian Andres Klode (juliank)]

Both the bug report and the comment #3 are user error with "If" and "acpi" respectively being in the wrong place in /etc/default/grub.