Key error at urbanairship/common.py L 66 #41

import urbanairship as ua
from local_credentials import uas

airshipauth = ua.Airship(**uas)

#creating a Static List:
new_static_list = ua.devices.StaticList(airshipauth, 'new_static_list')
new_static_list.create()
# it returns {'ok':True}
#uploading list
with open('users.csv', 'rb') as _file:
    new_static_list.upload(_file)
# ????

    new_static_list.upload(_file)
---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
<ipython-input-46-d4f457512c8d> in <module>()
----> 1 result.upload(_file)

~/anaconda3/envs/genericenv/lib/python3.6/site-packages/urbanairship/devices/static_lists.py in upload(self, csv_file)
     48             content_type='text/csv',
     49             version=3,
---> 50             encoding='gzip'
     51         )
     52         return response.json()

~/anaconda3/envs/genericenv/lib/python3.6/site-packages/urbanairship/core.py in _request(self, method, body, url, content_type, version, params, encoding)
     63             raise common.Unauthorized
     64         elif not (200 <= response.status_code < 300):
---> 65             raise common.AirshipFailure.from_response(response)
     66 
     67         return response

~/anaconda3/envs/genericenv/lib/python3.6/site-packages/urbanairship/common.py in from_response(cls, response)
     63             error = payload['error']
     64             error_code = payload['error_code']
---> 65             details = payload['details']
     66         except (ValueError, TypeError):
     67             error = response.reason

KeyError: 'details'