grub installation failed! I'm new in ubuntu and I was trying to install ubuntu alongside of my windows 10. :\

[Ashkan Rezaei]

I was trying to install ubuntu 20.04 LTS alongside of windows 10 on SSD.
what I expected was complete installation of ubuntu and happy ending without any problem! but I got an error that said something about 'grub installation failure' or something like that!
I'm new to ubuntu. :(

the second part of needed things are:
grub:
  Installed: (none)
  Candidate: (none)
  Version table:

I used to install ubuntu 18(I don't remember release number) LTS alongside of windows 10 on this machine earlier and I had the same problem those days too! :|
I'm not sure, am I doing something wrong? :'(

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
CurrentDesktop: ubuntu:GNOME
Date: Sat May 9 03:57:23 2020
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/ubuntu.seed maybe-ubiquity quiet splash ---
LiveMediaBuild: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
ProcEnviron:
 LANGUAGE=en_US.UTF-8
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 LC_NUMERIC=C.UTF-8
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

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

[Neil Fulcher (neilf377)]

I'm lost but the install hasn't worked