package grub-efi-amd64-signed 1.83+2.02~beta3-4ubuntu5 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1

[Per-Inge]

The computer has 3 boot-disks
sda with Ubuntu artful efi boot
sdb with W10 non efi boot
sdc with Ubuntu artful non efi boot

Problems earlier with grub on sda as sudo update-grub don't find the W10 installation.

ProblemType: Package
DistroRelease: Ubuntu 17.10
Package: grub-efi-amd64-signed 1.83+2.02~beta3-4ubuntu5
ProcVersionSignature: Ubuntu 4.10.0-21.23-generic 4.10.11
Uname: Linux 4.10.0-21-generic x86_64
ApportVersion: 2.20.5-0ubuntu4
Architecture: amd64
Date: Sat Jun 3 12:53:17 2017
DuplicateSignature:
 package:grub-efi-amd64-signed:1.83+2.02~beta3-4ubuntu5
 Setting up grub-efi-amd64-signed (1.83+2.02~beta3-4ubuntu5) ...
 grub-install: error: /usr/lib/grub/i386-pc/modinfo.sh doesn't exist. Please specify --target or --directory.
 dpkg: error processing package grub-efi-amd64-signed (--configure):
  subprocess installed post-installation script returned error exit status 1
ErrorMessage: subprocess installed post-installation script returned error exit status 1
InstallationDate: Installed on 2017-04-29 (35 days ago)
InstallationMedia: Ubuntu 17.10 "Artful Aardvark" - Alpha amd64 (20170428)
RelatedPackageVersions:
 dpkg 1.18.23ubuntu7
 apt 1.4.5
SourcePackage: grub2-signed
Title: package grub-efi-amd64-signed 1.83+2.02~beta3-4ubuntu5 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)