keystone-manage db_sync

エラー


Traceback (most recent call last):
  File "/usr/bin/keystone-manage", line 28, in
    cli.main(argv=sys.argv, config_files=config_files)
  File "/usr/lib/python2.7/dist-packages/keystone/cli.py", line 148, in main
    return run(cmd, (args[:1] + args[2:]))
  File "/usr/lib/python2.7/dist-packages/keystone/cli.py", line 134, in run
    return CMDS[cmd](argv=args).run()
  File "/usr/lib/python2.7/dist-packages/keystone/cli.py", line 36, in run
    return self.main()
  File "/usr/lib/python2.7/dist-packages/keystone/cli.py", line 55, in main
    driver = utils.import_object(getattr(CONF, k).driver)
  File "/usr/lib/python2.7/dist-packages/keystone/common/utils.py", line 60, in import_object
    __import__(import_str)
TypeError: __import__() argument 1 must be string, not None