Description of problem:
Glance via cinder with Unity backend is throwing connection errors. But cinder backend is working fine. See error below

019-03-31 01:35:43.598 33 ERROR glance_store._drivers.cinder [req-db5bd6ee-f946-4dc1-97cd-0bc424574529 af06afa62e584dff873e0ebc80c07b81 de68ddd9cfe8407982947db66f7b29f0 - default default] Exception while accessing to cinder volume 6120e260-cb27-4992-905f-b35d999e780c.: ClientException: Unable to fetch connection information from backend. (HTTP 500) (Request-ID: req-46ddc66d-5c88-4637-92e4-450cafb6b01a)
2019-03-31 01:35:43.598 33 ERROR glance_store._drivers.cinder Traceback (most recent call last):
2019-03-31 01:35:43.598 33 ERROR glance_store._drivers.cinder   File "/usr/lib/python2.7/site-packages/glance_store/_drivers/cinder.py", line 493, in _open_cinder_volume
2019-03-31 01:35:43.598 33 ERROR glance_store._drivers.cinder     connection_info = volume.initialize_connection(volume, properties)
2019-03-31 01:35:43.598 33 ERROR glance_store._drivers.cinder   File "/usr/lib/python2.7/site-packages/cinderclient/v2/volumes.py", line 94, in initialize_connection
2019-03-31 01:35:43.598 33 ERROR glance_store._drivers.cinder     return self.manager.initialize_connection(self, connector)
2019-03-31 01:35:43.598 33 ERROR glance_store._drivers.cinder   File "/usr/lib/python2.7/site-packages/cinderclient/v2/volumes.py", line 435, in initialize_connection
2019-03-31 01:35:43.598 33 ERROR glance_store._drivers.cinder     {'connector': connector})
2019-03-31 01:35:43.598 33 ERROR glance_store._drivers.cinder   File "/usr/lib/python2.7/site-packages/cinderclient/v2/volumes.py", line 365, in _action
2019-03-31 01:35:43.598 33 ERROR glance_store._drivers.cinder     resp, body = self.api.client.post(url, body=body)
2019-03-31 01:35:43.598 33 ERROR glance_store._drivers.cinder   File "/usr/lib/python2.7/site-packages/cinderclient/client.py", line 457, in post
2019-03-31 01:35:43.598 33 ERROR glance_store._drivers.cinder     return self._cs_request(url, 'POST', **kwargs)
2019-03-31 01:35:43.598 33 ERROR glance_store._drivers.cinder   File "/usr/lib/python2.7/site-packages/cinderclient/client.py", line 410, in _cs_request
2019-03-31 01:35:43.598 33 ERROR glance_store._drivers.cinder     resp, body = self.request(url, method, **kwargs)
2019-03-31 01:35:43.598 33 ERROR glance_store._drivers.cinder   File "/usr/lib/python2.7/site-packages/cinderclient/client.py", line 392, in request
2019-03-31 01:35:43.598 33 ERROR glance_store._drivers.cinder     raise exceptions.from_response(resp, body)
2019-03-31 01:35:43.598 33 ERROR glance_store._drivers.cinder ClientException: Unable to fetch connection information from backend. (HTTP 500) (Request-ID: req-46ddc66d-5c88-4637-92e4-450cafb6b01a)
2019-03-31 01:35:43.598 33 ERROR glance_store._drivers.cinder 

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