distrib upgrade from 20.10 to 21.04 crashes while do-release-upgrade -d

[Anton]

crash during dist upgrade from 20.10 to 21.04
command running withh root privilege

ProblemType: Bug
DistroRelease: Ubuntu 20.10
Package: ubuntu-release-upgrader-core 1:20.10.15
ProcVersionSignature: Ubuntu 5.8.0-50.56-generic 5.8.18
Uname: Linux 5.8.0-50-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu50.5
Architecture: amd64
CasperMD5CheckResult: skip
CrashDB: ubuntu
Date: Fri Apr 23 07:30:39 2021
InstallationDate: Installed on 2020-10-28 (176 days ago)
InstallationMedia: Ubuntu 20.10 "Groovy Gorilla" - Release amd64 (20201022)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to groovy on 2021-04-23 (0 days ago)
VarLogDistupgradeAptlog:
 Log time: 2021-04-23 07:30:21.622543
 Log time: 2021-04-23 07:30:24.470036
 Log time: 2021-04-23 07:30:39.695409
 Log time: 2021-04-23 07:30:41.437953