package nvidia-dkms-390 390.48-0ubuntu3 failed to install/upgrade: installed nvidia-dkms-390 package post-installation script subprocess returned error exit status 6

[SiggiTron]

after the fresh installation, this message was embedded

ProblemType: Package
DistroRelease: Ubuntu 18.04
Package: nvidia-dkms-390 390.48-0ubuntu3
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
Architecture: amd64
Date: Sat May 12 16:19:33 2018
ErrorMessage: installed nvidia-dkms-390 package post-installation script subprocess returned error exit status 6
InstallationDate: Installed on 2018-05-11 (0 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
Python3Details: /usr/bin/python3.6, Python 3.6.5, python3-minimal, 3.6.5-3
PythonDetails: /root/Error: command ['which', 'python'] failed with exit code 1:, Error: [Errno 2] Adresář nebo soubor neexistuje: "/root/Error: command ['which', 'python'] failed with exit code 1:": "/root/Error: command ['which', 'python'] failed with exit code 1:", unpackaged
RelatedPackageVersions:
 dpkg 1.19.0.5ubuntu2
 apt 1.6.1
SourcePackage: nvidia-graphics-drivers-390
Title: package nvidia-dkms-390 390.48-0ubuntu3 failed to install/upgrade: installed nvidia-dkms-390 package post-installation script subprocess returned error exit status 6
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

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