installation crashed before the end

[Luca]

I'm novice on Ubuntu and Linux in general. I remind the word "grab" in the error but nothing more.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: ubiquity 20.04.15
ProcVersionSignature: Ubuntu 5.4.0-26.30-lowlatency 5.4.30
Uname: Linux 5.4.0-26-lowlatency x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
CasperMD5CheckMismatches: ./boot/grub/efi.img
CasperMD5CheckResult: fail
CasperVersion: 1.445
Date: Sat May 16 23:12:20 2020
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/ubuntustudio.seed only-ubiquity quiet splash nomodeset ---
LiveMediaBuild: Ubuntu-Studio 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
ProcEnviron:
 LANGUAGE=it_IT.UTF-8
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=it_IT.UTF-8
 LC_NUMERIC=C.UTF-8
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.