Public bug reported: I upgraded this system to the Mate beta 1 and was hit by this during the process.
Rebooting and rerunning apt seems to have fixed it but gave an additional warning: W: APT had planned for dpkg to do more than it reported back (9 vs 13). Affected packages: virtualbox-ext-pack:amd64 ProblemType: Package DistroRelease: Ubuntu 17.10 Package: virtualbox-ext-pack 5.1.26-1 ProcVersionSignature: Ubuntu 4.12.0-12.13-generic 4.12.8 Uname: Linux 4.12.0-12-generic x86_64 ApportVersion: 2.20.7-0ubuntu1 AptOrdering: NULL: ConfigurePending Architecture: amd64 Date: Sat Sep 2 00:39:15 2017 DpkgHistoryLog: Start-Date: 2017-09-02 00:39:15 Requested-By: rui (1000) DpkgTerminalLog: Setting up virtualbox-ext-pack (5.1.26-1) ... virtualbox-ext-pack: downloading: http://download.virtualbox.org/virtualbox/5.1.26/Oracle_VM_VirtualBox_Extension_Pack-5.1.26.vbox-extpack The file will be downloaded into /usr/share/virtualbox-ext-pack dpkg: error processing package virtualbox-ext-pack (--configure): subprocess installed post-installation script returned error exit status 8 ErrorMessage: subprocess installed post-installation script returned error exit status 8 InstallationDate: Installed on 2017-02-20 (193 days ago) InstallationMedia: Ubuntu-MATE 17.04 "Zesty Zapus" - Alpha amd64 (20170125) PackageArchitecture: all Python3Details: /usr/bin/python3.6, Python 3.6.2, python3-minimal, 3.6.1-0ubuntu3 PythonDetails: /usr/bin/python2.7, Python 2.7.13, python-minimal, 2.7.13-2 RelatedPackageVersions: dpkg 1.18.24ubuntu1 apt 1.5~rc1~ubuntu1 SourcePackage: virtualbox-ext-pack Title: package virtualbox-ext-pack 5.1.26-1 failed to install/upgrade: subprocess installed post-installation script returned error exit status 8 UpgradeStatus: Upgraded to artful on 2017-09-02 (0 days ago) ** Affects: virtualbox-ext-pack (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-package artful -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1714631 Title: package virtualbox-ext-pack 5.1.26-1 failed to install/upgrade: subprocess installed post-installation script returned error exit status 8 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/virtualbox-ext-pack/+bug/1714631/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs