"Error while executing action Add Subnet to Provider: Failed to communicate with the external provider"

==> /var/log/neutron/server.log <==
2014-12-07 22:35:14.825 1061 INFO neutron.wsgi [-] (1061) accepted ('xxx.xxx.xxx.xxx', 42975)

2014-12-07 22:35:14.828 1061 INFO urllib3.connectionpool [-] Starting new HTTP connection (1): 127.0.0.1
2014-12-07 22:35:14.920 1061 INFO neutron.plugins.ml2.db [req-ba2a18ec-6e02-4526-99a8-27b35152781f None] Added segment e0ad11df-9c5a-4167-82ea-313dcc626661                                        of type flat for network 213c62ce-e167-4bb0-bd2d-720dd06bc970
2014-12-07 22:35:14.930 1061 INFO neutron.wsgi [req-ba2a18ec-6e02-4526-99a8-27b35152781f None]  - - [07/Dec/2014 22:35:14] "POST /v2.0/networ                                       ks HTTP/1.1" 201 527 0.103579