Ubuntu installer crashed 3/4 through initial steps

[Ronin]

Ubuntu Focal setup on USB, booted to "try Ubuntu" in safe video mode (regular mode would boot, but then the screen went blank).
Clicked "install Ubuntu", went through initial steps incl. timezone and installer crashed. No specific error message.

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
Date: Sun May 3 15:24:51 2020
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/ubuntu.seed maybe-ubiquity quiet splash nomodeset ---
LiveMediaBuild: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)