installer crashed when installing the os

[Ben Featherstone]

the installer failed to finish the install after all of the information was entered

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: ubiquity 20.04.4
ProcVersionSignature: Ubuntu 5.4.0-9.12-generic 5.4.3
Uname: Linux 5.4.0-9-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu15
Architecture: amd64
CasperVersion: 1.438
CurrentDesktop: ubuntu:GNOME
Date: Wed Feb 5 19:19:43 2020
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/ubuntu.seed only-ubiquity quiet splash ---
LiveMediaBuild: Ubuntu 20.04 LTS "Focal Fossa" - Alpha amd64 (20200124)
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)

[Launchpad Janitor (janitor)]

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

[Tim Jones (timjones105)]

The "mini" (Net) installer works perfectly for 20.04, whereas the Calamaris installer always crashes complaining about not being able to copy files...??