grub-efi-amd64-signed’ package failed to install into /target

[Jan g j]

i have tried installing ubuntu 18 on an acer SW312-31 with internal microSD emmc, but get the message grub was not installed, have tried clean install, dual boot, get same message with GRUB.
and i tried to install on a external SSD hard drive, from the acer but i get the same message with GRUB not install on taget..
 i can boot into it installed ubuntu 18 but can't install anything in there, due to grub-efi-amd64-signed..

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubiquity 18.04.14.14
ProcVersionSignature: Ubuntu 5.3.0-28.30~18.04.1-generic 5.3.13
Uname: Linux 5.3.0-28-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.9
Architecture: amd64
CasperVersion: 1.394.3
Date: Mon Mar 23 19:15:12 2020
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/ubuntu.seed boot=casper quiet splash ---
LiveMediaBuild: Ubuntu 18.04.4 LTS "Bionic Beaver" - Release amd64 (20200203.1)
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)