leapp upgrade fails in reboot phase with error 'Container el8userspace terminated by signal KILL' and enters dracut emergency shell

Issue

• After executed leapp upgrade and rebooted the system, upgrade fails with following messages and enters emergency shell

  STDERR:
  Container el8userspace terminated by signal KILL.
  ...
  ...
  Answerfile has been generated at /var/log/leapp/answerfile
  Container sysroot failed with error code 1.
  writing logs to disk and rebooting
  Spawning container sysroot on /sysroot.
  Press ^] three times within 1s to kill container.
  Container sysroot exited successfully.
  /bin/upgrade: line 19: /sysroot/var/tmp/system-upgrade.state: No such file or directory
  ...
  ...
  Generating "/run/initramfs/rdsosreport.txt"
  
  Entering emergency mode. Exit the shell to continue.
  Type "journalctl" to view system logs.
  You might want to save "/run/initramfs/rdsosreport.txt" to a USB stick or /boot
  after mounting them and attach it to a bug report.
  
  :/#