package grub-efi-amd64 2.02-2ubuntu8.15 failed to install/upgrade: installed grub-efi-amd64 package post-installation script subprocess returned error exit status 1

when installing upgrade from 16.04 to 18.04 on ubuntu i got loads of errors tat i dont understand:
my system has uefi secure boot enabled in the firmware so the following kernels present in the system were unsigned, 5.5.1-050501-generic , then the rest of the message tells me grub wont be updated till these kernels are replaced with signed kernels.

thats one thing

sems to me the easiest thing is to back up files and the wie the system and install the latest ubuntu from fresh. Ive been getting lots of issues from updates to 16.04 with a regular unspecified error every logon which pops up a message window which is totally generic.

ProblemType: Package
DistroRelease: Ubuntu 18.04
Package: grub-efi-amd64 2.02-2ubuntu8.15
Uname: Linux 5.5.1-050501-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.14
Architecture: amd64
Date: Thu Apr 2 18:36:49 2020
ErrorMessage: installed grub-efi-amd64 package post-installation script subprocess returned error exit status 1
InstallationDate: Installed on 2016-10-23 (1257 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.5.1-050501-generic root=UUID=c0614860-7c44-4bd5-af20-a762a9c1a68c ro quiet splash vt.handoff=7
Python3Details: /usr/bin/python3.6, Python 3.6.9, python3-minimal, 3.6.7-1~18.04
PythonDetails: /usr/bin/python2.7, Python 2.7.17, python-minimal, 2.7.15~rc1-1
RelatedPackageVersions:
 dpkg 1.19.0.5ubuntu2.3
 apt 1.6.12
SourcePackage: grub2
Title: package grub-efi-amd64 2.02-2ubuntu8.15 failed to install/upgrade: installed grub-efi-amd64 package post-installation script subprocess returned error exit status 1
UpgradeStatus: Upgraded to bionic on 2020-04-02 (0 days ago)