Crash installing

[Dr. José Ra. Portillo aka Zifra]

May be an error in my disk. I cannot enter my session in Ubuntu 18. Install Ubuntu 20 has not been possible.

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: Thu Apr 23 21:21:41 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=es_ES.UTF-8
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=es_ES.UTF-8
 LC_NUMERIC=C.UTF-8
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)

[Steve Langasek (vorlon)]

The ultimate error in your log is:

Apr 23 19:21:32 ubuntu ubiquity: AssertionError: Failed to mount the target: /target

Could you describe what install option you were trying to use?

[Alex Kudentsov (alexk37)]

I've just had exactly the same problem trying to make a fresh install from a bootable USB created with Ubuntu 18.04 Startup Disk Creator tool.
The option I chose was a fresh install using an entire SSD disk and ZFS filesystem.
After the crash I killed ubiquity and a desktop session was opened. I launched the installation again and it went ok.
Both times I chose exactly the same install options, the only difference is that during my first installation attempt which failed I tried to open different install options several times but didn't proceed and just pressed Back to go to the main install option menu.
Thanks

[Dr. José Ra. Portillo aka Zifra (josera)]

The instalation was standard. After some tries, I install Ubuntu20 without problem.

[Launchpad Janitor (janitor)]

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

[Alex Kudentsov (alexk37)]

I'm having the same problem replacing 18.04 with 20.4, in my case it crashed saying that the disk is currently in use followed by

>Ubiquity: AssertionError: Failed to mount the target: /target

I also have a video of the failed installation flow, I reproduced the problem several times but not the last few times I tried, maybe there is some detail in the flow I'm missing. Let me know if any other info is needed.