package friendly-recovery 0.2.31 failed to install/upgrade: subprocess installed post-installation script returned error exit status 2

[Mohit Soni]

I just upgraded my ubuntu from 14.04 to 16.04. During installation I received this message

package friendly-recovery 0.2.31 failed to install/upgrade: subprocess installed post-installation script returned error exit status 2

Then it automatically asked me to report the bug.

ProblemType: Package
DistroRelease: Ubuntu 16.04
Package: friendly-recovery 0.2.31
ProcVersionSignature: Ubuntu 3.13.0-71.114-generic 3.13.11-ckt29
Uname: Linux 3.13.0-71-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.6
Architecture: amd64
Date: Sat Jun 24 14:01:39 2017
DuplicateSignature:
 package:friendly-recovery:0.2.31
 Setting up friendly-recovery (0.2.31) ...
 /usr/sbin/grub-mkconfig: 41: /etc/default/grub: Syntax error: Bad function name
 dpkg: error processing package friendly-recovery (--configure):
  subprocess installed post-installation script returned error exit status 2
ErrorMessage: subprocess installed post-installation script returned error exit status 2
InstallationDate: Installed on 2015-11-13 (588 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
PackageArchitecture: all
RelatedPackageVersions:
 dpkg 1.18.4ubuntu1.2
 apt 1.2.20
SourcePackage: friendly-recovery
Title: package friendly-recovery 0.2.31 failed to install/upgrade: subprocess installed post-installation script returned error exit status 2
UpgradeStatus: Upgraded to xenial on 2017-06-24 (0 days ago)

[Launchpad Janitor (janitor)]

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

[Juhani Numminen (jsonic)]

The error seems to be: "/usr/sbin/grub-mkconfig: 41: /etc/default/grub: Syntax error: Bad function name".

Please remove "save()" and "exit()" from your /etc/default/grub file.