Unable to locate models.dat file

[Janos G. Komaromi]

Hp printer worked on 16.04 but it fails after distribution upgrade to 18.04. Based on solved bug #1744340 I checked libsane-hpaio and hplip packages. They were all OK after removing them and reinstalling them - just to make sure. However, apt install libsane-hpaio complained about missing /etc/hp/hplip.conf (?). Regardless, running hp-setup cannot complete the download step because of incorrect checksum. This is when I started this ubuntu-bug -w command.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: xfce4-terminal 0.8.7.4-0ubuntu0.18.04.1
ProcVersionSignature: Ubuntu 4.15.0-36.39-generic 4.15.18
Uname: Linux 4.15.0-36-generic i686
ApportVersion: 2.20.9-0ubuntu7.4
Architecture: i386
CurrentDesktop: XFCE
Date: Thu Oct 11 15:59:14 2018
ExecutablePath: /usr/bin/xfce4-terminal
InstallationDate: Installed on 2016-12-13 (667 days ago)
InstallationMedia: Xubuntu 16.04.1 LTS "Xenial Xerus" - Release i386 (20160719)
SourcePackage: xfce4-terminal
UpgradeStatus: Upgraded to bionic on 2018-10-01 (9 days ago)

[Launchpad Janitor (janitor)]

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

[Janos G. Komaromi (jankom)]

This may help pinpoint the cause: I did a virgin install of 18.04 on the same machine, and now hplip works, printer is found, printing (and scanning as well) is OK. Therefore the problem must be with the distribution upgrade process.