grub install failure during Ubuntu 20.04 install

[Chris Pechacek]

Following steps to encrypt drive, https://help.ubuntu.com/community/Full_Disk_Encryption_Howto_2019
Had swap error on first attempts, so, last try skipped creating swap volume.
During installation, fatal error of Grub-install failed.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: ubiquity 20.04.15.17
ProcVersionSignature: Ubuntu 5.11.0-27.29~20.04.1-generic 5.11.22
Uname: Linux 5.11.0-27-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu27.18
Architecture: amd64
CasperMD5CheckMismatches: ./pool/restricted/n/nvidia-graphics-drivers-460/libnvidia-decode-460_460.91.03-0ubuntu0.20.04.1_amd64.deb
CasperMD5CheckResult: skip
CasperVersion: 1.445.1
Date: Fri Nov 26 04:25:32 2021
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/ubuntu.seed maybe-ubiquity quiet splash ---
LiveMediaBuild: Ubuntu 20.04.3 LTS "Focal Fossa" - Release amd64 (20210819)
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)