installer crashed on efi zfs install. unable to mount /target

I've tried to install XUbuntu on USB flash drive with EFI and ZFS. Installer have crashed during installation. Noticed the message that said something about failure mounting /target.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: ubiquity 20.04.15.10
ProcVersionSignature: Ubuntu 5.8.0-43.49~20.04.1-generic 5.8.18
Uname: Linux 5.8.0-43-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu27.16
Architecture: amd64
CasperMD5CheckResult: pass
CasperVersion: 1.445.1
Date: Thu Jun 3 10:59:47 2021
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/xubuntu.seed only-ubiquity quiet splash ---
LiveMediaBuild: Xubuntu 20.04.2.0 LTS "Focal Fossa" - Release amd64 (20210209.1)
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: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)