Why is there such an error ? 2021-10-27 06:33:30,996+0800 INFO (jsonrpc/3) [api.host] FINISH getStats error=<Fault 1: "<type 'exceptions.AttributeError'>:'NoneType' object has no attribute 'statistics'"> from=::ffff:10.200.211.80,48086 (api:52) 2021-10-27 06:33:30,997+0800 ERROR (jsonrpc/3) [jsonrpc.JsonRpcServer] Internal server error (__init__:350) Traceback (most recent call last): File "/usr/lib/python2.7/site-packages/yajsonrpc/__init__.py", line 345, in _handle_request res = method(**params) File "/usr/lib/python2.7/site-packages/vdsm/rpc/Bridge.py", line 198, in _dynamicMethod result = fn(*methodArgs) File "<string>", line 2, in getStats File "/usr/lib/python2.7/site-packages/vdsm/common/api.py", line 50, in method ret = func(*args, **kwargs) File "/usr/lib/python2.7/site-packages/vdsm/API.py", line 1435, in getStats multipath=True)} File "/usr/lib/python2.7/site-packages/vdsm/host/api.py", line 77, in get_stats ret.update(cif.mom.getKsmStats()) File "/usr/lib/python2.7/site-packages/vdsm/momIF.py", line 67, in getKsmStats stats = self._mom.getStatistics()['host'] File "/usr/lib64/python2.7/xmlrpclib.py", line 1233, in __call__ return self.__send(self.__name, args) File "/usr/lib64/python2.7/xmlrpclib.py", line 1591, in __request verbose=self.__verbose File "/usr/lib64/python2.7/xmlrpclib.py", line 1273, in request return self.single_request(host, handler, request_body, verbose) File "/usr/lib64/python2.7/xmlrpclib.py", line 1306, in single_request return self.parse_response(response) File "/usr/lib64/python2.7/xmlrpclib.py", line 1482, in parse_response return u.close() File "/usr/lib64/python2.7/xmlrpclib.py", line 794, in close raise Fault(**self._stack[0]) Fault: <Fault 1: "<type 'exceptions.AttributeError'>:'NoneType' object has no attribute 'statistics'"> 2021-10-27 06:33:30,997+0800 INFO (jsonrpc/3) [jsonrpc.JsonRpcServer] RPC call Host.getStats failed (error -32603) in 0.04 seconds (__init__:312)