PostInstall script error

[Humphrey van Polanen Petel]

upgrading from 16.04 to 18.04
from /var/log/dist-upgrade/main-log
ERROR got error from PostInstallScript ./xorg_fix_proprietary.py (g-exec-error-quark: Failed to execute child process "./xorg_fix_proprietary.py" (No such file or directory) (8))

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: linux-image-4.15.0-34-generic 4.15.0-34.37
ProcVersionSignature: Ubuntu 4.15.0-34.37-generic 4.15.18
Uname: Linux 4.15.0-34-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.3
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: humphrey 1925 F.... pulseaudio
CurrentDesktop: Unity:Unity7:ubuntu
Date: Wed Sep 26 09:53:31 2018
HibernationDevice: RESUME=UUID=2023ea8a-8243-4518-9418-125a5d452287
InstallationDate: Installed on 2017-03-27 (547 days ago)
InstallationMedia: Ubuntu 16.04.2 LTS "Xenial Xerus" - Release amd64 (20170215.2)
IwConfig:
 lo no wireless extensions.

 enp0s3 no wireless extensions.
Lsusb:
 Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 001 Device 002: ID 80ee:0021 VirtualBox USB Tablet
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: innotek GmbH VirtualBox
ProcFB: 0 vboxdrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-34-generic root=UUID=f847e39f-82a1-46a1-b55e-879dbcf4ea3a ro nosplash
RelatedPackageVersions:
 linux-restricted-modules-4.15.0-34-generic N/A
 linux-backports-modules-4.15.0-34-generic N/A
 linux-firmware 1.173.1
RfKill:

SourcePackage: linux
StagingDrivers: vboxvideo
UpgradeStatus: Upgraded to bionic on 2018-09-25 (0 days ago)
dmi.bios.date: 12/01/2006
dmi.bios.vendor: innotek GmbH
dmi.bios.version: VirtualBox
dmi.board.name: VirtualBox
dmi.board.vendor: Oracle Corporation
dmi.board.version: 1.2
dmi.chassis.type: 1
dmi.chassis.vendor: Oracle Corporation
dmi.modalias: dmi:bvninnotekGmbH:bvrVirtualBox:bd12/01/2006:svninnotekGmbH:pnVirtualBox:pvr1.2:rvnOracleCorporation:rnVirtualBox:rvr1.2:cvnOracleCorporation:ct1:cvr:
dmi.product.family: Virtual Machine
dmi.product.name: VirtualBox
dmi.product.version: 1.2
dmi.sys.vendor: innotek GmbH

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This change was made by a bot.

[Sebastien Bacher (seb128)]

There is a similar warning/error in the description of bug #1826025 (though that's not what the report is about)