Version-Release number of selected component:
python2-dnf-1.1.5-1.fc23

Additional info:
reporter:       libreport-2.6.3
cmdline:        /usr/bin/python /usr/bin/dnf-2 migrate
dso_list:       python-dnf-plugins-extras-migrate-0.0.12-1.fc23.noarch
executable:     /usr/bin/dnf-2
kernel:         4.3.3-300.fc23.x86_64
runlevel:       N 5
type:           Python
uid:            1000

Truncated backtrace:
migrate.py:139:migrate_history_pkgs:AttributeError: 'NoneType' object has no attribute 'execute'

Traceback (most recent call last):
  File "/usr/bin/dnf-2", line 58, in <module>
    main.user_main(sys.argv[1:], exit_code=True)
  File "/usr/lib/python2.7/site-packages/dnf/cli/main.py", line 174, in user_main
    errcode = main(args)
  File "/usr/lib/python2.7/site-packages/dnf/cli/main.py", line 60, in main
    return _main(base, args)
  File "/usr/lib/python2.7/site-packages/dnf/cli/main.py", line 112, in _main
    cli.run()
  File "/usr/lib/python2.7/site-packages/dnf/cli/cli.py", line 1095, in run
    return self.command.run(self.base.extcmds)
  File "/usr/lib/python2.7/site-packages/dnf-plugins/migrate.py", line 117, in run
    self.migrate_history()
  File "/usr/lib/python2.7/site-packages/dnf-plugins/migrate.py", line 133, in migrate_history
    self.migrate_history_pkgs(yum_history, dnf_history)
  File "/usr/lib/python2.7/site-packages/dnf-plugins/migrate.py", line 139, in migrate_history_pkgs
    yum_cur.execute("""
AttributeError: 'NoneType' object has no attribute 'execute'

Local variables in innermost frame:
yum_hist: <dnf.yum.history.YumHistory object at 0x7f3aefd03910>
yum_cur: None
self: <dnf.plugin.dynamic.migrate.MigrateCommand object at 0x7f3aefd03990>
dnf_hist: <dnf.yum.history.YumHistory object at 0x7f3aee6674d0>

Potential duplicate: bug 1266768