the 'grub-efi-amd64-signed' package failed to install Ubuntu Mate 18.04, and there was no quick and effective information about the success ...

[JC Serra]

I just uninstalled Debian to install Ubuntu. I've been working on this desktop - along with Mac and Windows - never had a similar problem

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubiquity 18.04.14
ProcVersionSignature: Ubuntu 4.15.0-20.21-generic 4.15.17
Uname: Linux 4.15.0-20-generic x86_64
ApportVersion: 2.20.9-0ubuntu7
Architecture: amd64
CasperVersion: 1.394
Date: Wed May 2 20:50:44 2018
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/ubuntu-mate.seed boot=casper only-ubiquity quiet splash ---
LiveMediaBuild: Ubuntu-MATE 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
ProcEnviron:
 LANGUAGE=pt_PT.UTF-8
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=pt_PT.UTF-8
 LC_NUMERIC=C.UTF-8
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)