"Fatal error no grub pakage intstalled."

[Muhammad Arsalan]

I want to erase complete window 7 and do not want to erase or remove my data in e and f drive but c drive have window so that is the main target to remove that bug window 7 and install ubuntu that i have make boot on my usb drive. Every time it gives an error of grub and show "Fatal error no grub pakage intstalled."

please help me if you got my point

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: ubiquity 20.04.15.19
ProcVersionSignature: Ubuntu 5.13.0-30.33~20.04.1-generic 5.13.19
Uname: Linux 5.13.0-30-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu27.21
Architecture: amd64
CasperMD5CheckResult: pass
CasperVersion: 1.445.1
Date: Fri Mar 25 15:41:47 2022
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/ubuntu.seed maybe-ubiquity quiet splash ---
LiveMediaBuild: Ubuntu 20.04.4 LTS "Focal Fossa" - Release amd64 (20220223)
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)