package grub-pc 1.99-21ubuntu3.1 failed to install/upgrade: subprocess installed post-installation script returned error exit status 127

[Alexis De la Vega]

ubuntu 12.04 using wubi
after software update

ProblemType: Package
DistroRelease: Ubuntu 12.04
Package: grub-pc 1.99-21ubuntu3.1
ProcVersionSignature: Ubuntu 3.2.0-23.36-generic 3.2.14
Uname: Linux 3.2.0-23-generic x86_64
NonfreeKernelModules: fglrx
ApportVersion: 2.0.1-0ubuntu8
Architecture: amd64
Date: Wed Jun 6 17:53:19 2012
ErrorMessage: subprocess installed post-installation script returned error exit status 127
InvalidGrubScript: /etc/default/grub
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-23-generic root=UUID=B686006286002609 loop=/hostname/disks/root.disk ro quiet splash vt.handoff=7
SourcePackage: grub2
Title: package grub-pc 1.99-21ubuntu3.1 failed to install/upgrade: subprocess installed post-installation script returned error exit status 127
UpgradeStatus: No upgrade log present (probably fresh install)

[Steve Langasek (vorlon)]

The error in the logs is:

> /usr/sbin/grub-mkconfig: 12: /etc/default/grub: quiet: not found
> run-parts: /etc/kernel/postinst.d/zz-update-grub exited with return code 127

This indicates an incorrect manual edit of /etc/default/grub that has broken the syntax of the file - not a bug in the grub package. You will need to fix this file so that it declares variables using correct shell syntax (no spaces around equal signs; quotes around any values that contain spaces).