Hello, I'm having this error when I try to create a VM:

2015-09-15 01:50:15.831 11736 ERROR neutron.notifiers.nova [-] Failed to notify nova on events: [{'status': 'completed', 'tag': u'6abdaeb9-1b38-40cd-91b6-5465c33e1943', 'name': 'network-vif-plugged', 'server_uuid': u'6a296787-8ee1-427d-80ac-fb2f1ef8dfed'}]
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova Traceback (most recent call last):
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova   File "/usr/lib/python2.7/dist-packages/neutron/notifiers/nova.py", line 243, in send_events
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova     batched_events)
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova   File "/usr/lib/python2.7/dist-packages/novaclient/v2/contrib/server_external_events.py", line 39, in create
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova     return_raw=True)
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova   File "/usr/lib/python2.7/dist-packages/novaclient/base.py", line 152, in _create
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova     _resp, body = self.api.client.post(url, body=body)
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova   File "/usr/lib/python2.7/dist-packages/keystoneclient/adapter.py", line 170, in post
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova     return self.request(url, 'POST', **kwargs)
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova   File "/usr/lib/python2.7/dist-packages/novaclient/client.py", line 89, in request
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova     **kwargs)
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova   File "/usr/lib/python2.7/dist-packages/keystoneclient/adapter.py", line 200, in request
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova     resp = super(LegacyJsonAdapter, self).request(*args, **kwargs)
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova   File "/usr/lib/python2.7/dist-packages/keystoneclient/adapter.py", line 89, in request
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova     return self.session.request(url, method, **kwargs)
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova   File "/usr/lib/python2.7/dist-packages/keystoneclient/utils.py", line 318, in inner
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova     return func(*args, **kwargs)
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova   File "/usr/lib/python2.7/dist-packages/keystoneclient/session.py", line 307, in request
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova     auth_headers = self.get_auth_headers(auth)
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova   File "/usr/lib/python2.7/dist-packages/keystoneclient/session.py", line 589, in get_auth_headers
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova     return auth.get_headers(self, **kwargs)
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova   File "/usr/lib/python2.7/dist-packages/keystoneclient/auth/base.py", line 114, in get_headers
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova     token = self.get_token(session)
2015-09-15 01:50:15.831 11736 TRACE neutron.notifiers.nova   File "/usr/lib/python2.7/dist-packages/keystoneclient/auth/identity/base.py", line 104, in get_token
2015-09-15 01:50:15 ...