the installer crashes itself and won't continue installation

[fedfef]

no further information. Maybe you can check the log that I attached?

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubiquity 2.21.63.10
ProcVersionSignature: Ubuntu 4.15.0-45.48~16.04.1-generic 4.15.18
Uname: Linux 4.15.0-45-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.18
Architecture: amd64
CasperVersion: 1.376.2
Date: Mon Oct 5 16:40:30 2020
InstallCmdLine: initrd=/casper/initrd file=/cdrom/preseed/lubuntu.seed boot=casper only-ubiquity quiet splash --- BOOT_IMAGE=/casper/vmlinuz
LiveMediaBuild: Lubuntu 16.04.6 LTS "Xenial Xerus" - Release amd64 (20190227)
ProcEnviron:
 LANGUAGE=ru_RU.UTF-8
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=ru_RU.UTF-8
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)