Installer crashes when running grub-installer.

[Mohammad Mahdi]

Installer crashes when running grab-installer it said it can not install /cow. Please check that.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: ubiquity 20.04.15.10
ProcVersionSignature: Ubuntu 5.8.0-43.49~20.04.1-generic 5.8.18
Uname: Linux 5.8.0-43-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu27.16
Architecture: amd64
CasperMD5CheckResult: fail
CasperVersion: 1.445.1
CurrentDesktop: ubuntu:GNOME
Date: Sun Jul 25 08:53:46 2021
InstallCmdLine: bootkbd=us console-setup/layoutcode=en_US console-setup/variantcode=nodeadkeys locale=us_us persistent noprompt cdrom-detect/try-usb=true file=/cdrom/preseed/ubuntu.seed boot=casper initrd=/casper/initrd splash -- maybe-ubiquity
LiveMediaBuild: Ubuntu 20.04.2.0 LTS "Focal Fossa" - Release amd64 (20210209.1)
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)