JSON RPC request to OpenEMS Edge returns 503 code

Question

I'm trying to send a JSON RPC request to an OpenEMS Edge instance from a python script, but am getting a 503 error in response. I know the Edge instance is fine because a JSONRPC request from Postman works.

My Postman API call:

POST: http://localhost:8084/jsonrpc

Added headers: Basic Authorisation header

Body:

{ "method": "getEdgeConfig",
  "params": {}
}

Returns a valid json.

The same in python returns an error:

url='http://localhost:8084/jsonrpc'
headers = {'Authorization': 'Basic YWRtaW46YWRtaW4=',
        'Accept': '*/*',
        'Content-Type': 'application/json',
        }
body = {"method": "getEdgeConfig",
        "params": {}
        }
response = requests.post(url, headers=headers, json=body)

Returns a 503: Service Unavailable status