When I was installing, I got a pop-up saying: fatal error, executing "grub-install"

[Daniel Cupking]

I'm not an expert.

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: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu50
Architecture: amd64
CasperMD5CheckResult: pass
CasperVersion: 1.455
CurrentDesktop: ubuntu:GNOME
Date: Sun Nov 22 21:50:40 2020
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/ubuntu.seed maybe-ubiquity quiet splash ---
LiveMediaBuild: Ubuntu 20.10 "Groovy Gorilla" - Release amd64 (20201022)
ProcEnviron:
 LANGUAGE=en_US.UTF-8
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 LC_NUMERIC=C.UTF-8
RebootRequiredPkgs:
 linux-image-5.8.0-29-generic
 linux-base
 linux-image-5.8.0-25-generic
 linux-base
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

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

[Nathan Rennie-Waldock (nathan-renniewaldock)]

Nov 22 20:42:26 ubuntu grub-installer: info: Running chroot /target grub-install --force --target x86_64-efi "/dev/sda"
Nov 22 20:42:26 ubuntu grub-installer: Installing for x86_64-efi platform.
Nov 22 20:42:27 ubuntu grub-installer: grub-install: warning: Internal error.
Nov 22 20:42:27 ubuntu grub-installer: grub-install: error: failed to register the EFI boot entry: Operation not permitted.
Nov 22 20:42:27 ubuntu grub-installer: error: Running 'grub-install --force --target x86_64-efi "/dev/sda"' failed.

I think I know what's causing this. I'll see if I can reproduce it.