GRUB installation failed > inastallation program crash

[massimo]

I was installing Xubuntu 18.04 from sdb usb-pen on sda next to win 7 on fujitsu lifebook A512

#1 error message:

Installazione di GRUB non riuscita - L'installazione del pacchetto "grub-efi-amd64-signed" in /target/ non è riuscita [...]

P.S. the system is boot or legacy mode, not UEFI!

#2 error message:

Il programma di installazione è andato in crash - [...]

#3 then crash

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubiquity 18.04.14.12
ProcVersionSignature: Ubuntu 5.0.0-23.24~18.04.1-generic 5.0.15
Uname: Linux 5.0.0-23-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.7
Architecture: amd64
CasperVersion: 1.394
Date: Tue Dec 3 17:02:12 2019
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/xubuntu.seed boot=casper quiet splash ---
LiveMediaBuild: Xubuntu 18.04.3 LTS "Bionic Beaver" - Release amd64 (20190805)
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)