xubunto 17.04 to 17.10 upgrade. old grub setup was created manually during install on encrypted lvm volumes. package grub-efi-amd64-signed 1.85+2.02~beta3-4ubuntu7 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1

[nilshalvard]

i have no idea what the problem was. just got this during upgrade.

ProblemType: Package
DistroRelease: Ubuntu 17.10
Package: grub-efi-amd64-signed 1.85+2.02~beta3-4ubuntu7
ProcVersionSignature: Ubuntu 4.13.0-25.29-generic 4.13.13
Uname: Linux 4.13.0-25-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia_drm nvidia_modeset nvidia
ApportVersion: 2.20.7-0ubuntu3.7
Architecture: amd64
Date: Sun Jan 14 23:07:41 2018
ErrorMessage: subprocess installed post-installation script returned error exit status 1
InstallationDate: Installed on 2018-01-03 (11 days ago)
InstallationMedia: Xubuntu 17.04 "Zesty Zapus" - Release amd64 (20170412)
Python3Details: /usr/bin/python3.6, Python 3.6.3, python3-minimal, 3.6.3-0ubuntu2
PythonDetails: /usr/bin/python2.7, Python 2.7.14, python-minimal, 2.7.14-2ubuntu1
RelatedPackageVersions:
 dpkg 1.18.24ubuntu1
 apt 1.5.1
SourcePackage: grub2-signed
Title: package grub-efi-amd64-signed 1.85+2.02~beta3-4ubuntu7 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1
UpgradeStatus: Upgraded to artful on 2018-01-14 (0 days ago)