"Excecuting'grub-install/dev/sda5' failed" during ubuntu instalation

[Agung Santoso]

When installing ubuntu-20.10-desktop-amd64.
i got alert this "No EFI partition was found.This system........the instalation process may fail"
and i choose 'continue' button. Then warning as mention in summary appear.

ProblemType: Bug
DistroRelease: Ubuntu 20.10
Package: ubiquity 20.10.13
ProcVersionSignature: Ubuntu 5.8.0-25.26-generic 5.8.14
Uname: Linux 5.8.0-25-generic x86_64
NonfreeKernelModules: wl zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu50
Architecture: amd64
CasperMD5CheckResult: pass
CasperVersion: 1.455
Date: Mon Nov 9 23:01:53 2020
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/ubuntu.seed maybe-ubiquity quiet splash ---
LiveMediaBuild: Ubuntu 20.10 "Groovy Gorilla" - Release amd64 (20201022)
RebootRequiredPkgs:
 linux-image-5.8.0-25-generic
 linux-base
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)