Cannot install ubuntu bootloader I think

[The Colourful Jester]

Trying to install Ubuntu Mate 20.04 along Windows 10.

Error is the same as below.

#992379 Installer crashed. Created separate /boot partition, could not install, fatal error occured
Confirmed (3 comments) last updated 2014-12-16 view this bug

I created separate parition /boot, /, /home. While trying to install ubutnu 12.04 LTS, the installer crashed, (even though I can see a message in background, installation finished, continue testing or restart.) Apparently, the bootloader cannot be installed in /boot partition(250MiB). Tried to install on Windows 7 bootloader, Windows 8 Bootloader, /dev/sda, /(root), but nothing worked. The other operations available were continue without installing bootloader, or cancel the installation.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: ubiquity 20.04.15
ProcVersionSignature: Ubuntu 5.4.0-26.30-generic 5.4.30
Uname: Linux 5.4.0-26-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
CasperMD5CheckResult: pass
CasperVersion: 1.445
Date: Wed Oct 7 23:35:57 2020
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/ubuntu-mate.seed quiet splash ---
LiveMediaBuild: Ubuntu-MATE 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)

[The Colourful Jester (thecolourfuljester)]

Tried some solutions from googling the fault, but so far nothing has yet worked.

Will next try to install from a USB instead of a DVD.