尝试在openstack设置中运行nova list cli命令时，将出现以下错误：
NoneType“对象没有属性”getitem'debug(Shell:777 ) nonetype ' objecthasnoattribute ' _ _ getitem _ _”
跟踪后退(mostrecentcalllast ) :
文件'/opt/stack/python-nova client/nova client/shell.py '，line 774，in main
文件'/opt/stack/python-nova client/nova client/shell.py '，line 685，in main
self.cs.authenticate (
文件'/opt/stack/python-nova client/nova client/v1 _1/client.py '，line 169，in authenticate
self.client.authenticate (
文件'/opt/stack/python-nova client/nova client/client.py '，line 382，in authenticate
auth _ URL=self._ v2 _ auth (auth _ URL )
文件'/opt/stack/python-nova client/nova client/client.py '，line 469，in _v2_auth
返回自我. _身份(URL，body ) )。
file '/opt/stack/python-nova client/nova client/client.py '，line 484，in _authenticate
return self._ extract _ service _ catalog (URL、resp、respbody )。
file '/opt/stack/python-nova client/nova client/client.py '，line 307，in _extract_service_catalog
self.auth _ token=self.service _ catalog.get _ token (
file '/opt/stack/python-nova client/nova client/service _ catalog.py '，line 29，in get_token
return self.catalog [ ' access ' ] [ ' token ' ] [ ' id ' ]
error : ' nonetype ' objecthasnoattribute ' _ _ getitem _
那是什么意思？ 我的openstack设置有什么问题吗？ 还是与python相关的错误？