package cups-pk-helper 0.2.6-1ubuntu1.2 failed to install/upgrade: installed cups-pk-helper package post-installation script subprocess returned error exit status 1

Setting up cups-pk-helper (0.2.6-1ubuntu1.2) ...
useradd: failure while writing changes to /etc/passwd
adduser: `/usr/sbin/useradd -d /home/cups-pk-helper -g lpadmin -s /usr/sbin/nologin -u 137 cups-pk-helper' returned error code 1. Exiting.
dpkg: error processing package cups-pk-helper (--configure):
 installed cups-pk-helper package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
 cups-pk-helper

ProblemType: Package
DistroRelease: Ubuntu 18.04
Package: cups-pk-helper 0.2.6-1ubuntu1.2
ProcVersionSignature: Ubuntu 4.15.0-20.21-generic 4.15.17
Uname: Linux 4.15.0-20-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.2
Architecture: amd64
Date: Sat Jun 16 07:45:48 2018
ErrorMessage: installed cups-pk-helper package post-installation script subprocess returned error exit status 1
InstallationDate: Installed on 2017-01-07 (525 days ago)
InstallationMedia: Ubuntu 16.10 "Yakkety Yak" - Release amd64 (20161012.2)
Python3Details: /usr/bin/python3.6, Python 3.6.5, python3-minimal, 3.6.5-3
PythonDetails: /usr/bin/python2.7, Python 2.7.15rc1, python-minimal, 2.7.15~rc1-1
RelatedPackageVersions:
 dpkg 1.19.0.5ubuntu2
 apt 1.6.1
SourcePackage: cups-pk-helper
Title: package cups-pk-helper 0.2.6-1ubuntu1.2 failed to install/upgrade: installed cups-pk-helper package post-installation script subprocess returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)