package virtualbox-ext-pack 5.2.10-3 failed to install/upgrade: installed virtualbox-ext-pack package post-installation script subprocess returned error exit status 4

[Arnaud]

Error in upgrading from 17.10 (last updated approx. 2 weeks ago) to 18.04, yesterday.
This upgrade seems to have installed everything else but aborted just before the cleaning phase and said a reboot could result in a non working system. So i haven't dared do it until this moment. I have given priority to rsync'ing all my personal directory on an external disk last night, since i had never taken time to do a backup before.

So now i just get a line of error message if i try to reinstall the package:

        E: Internal Error, No file name for virtualbox-ext-pack:amd64

(Now i'm going to reboot, hoping that only Virtualbox is broken...)

-----

Description: Ubuntu 18.04 LTS
Release: 18.04

virtualbox-ext-pack:
  Installé : 5.2.10-3
  Candidat : 5.2.10-3
 Table de version :
 *** 5.2.10-3 500
        500 http://fr.archive.ubuntu.com/ubuntu bionic/multiverse amd64 Packages
        500 http://fr.archive.ubuntu.com/ubuntu bionic/multiverse i386 Packages
        100 /var/lib/dpkg/status

ProblemType: Package
DistroRelease: Ubuntu 18.04
Package: virtualbox-ext-pack 5.2.10-3
ProcVersionSignature: Ubuntu 4.13.0-39.44-generic 4.13.16
Uname: Linux 4.13.0-39-generic x86_64
ApportVersion: 2.20.9-0ubuntu7
Architecture: amd64
Date: Mon May 7 01:20:25 2018
ErrorMessage: installed virtualbox-ext-pack package post-installation script subprocess returned error exit status 4
InstallationDate: Installed on 2017-12-12 (145 days ago)
InstallationMedia: Ubuntu-GNOME 17.04 "Zesty Zapus" - Release amd64 (20170412)
PackageArchitecture: all
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: virtualbox-ext-pack
Title: package virtualbox-ext-pack 5.2.10-3 failed to install/upgrade: installed virtualbox-ext-pack package post-installation script subprocess returned error exit status 4
UpgradeStatus: Upgraded to bionic on 2018-05-06 (0 days ago)

[Launchpad Janitor (janitor)]

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