If I use alpaca-trade-api version 0.46, the simpleStream.py example demo works:
pip3 install alpaca_trade_api==0.46
python simpleStream.py --all (under alpaca-trade-api-python/examples directory from github repository)
Example Output (seems OK):
2020-06-23 04:28:43.841834   debug:  Entity({‘ev’: ‘status’, ‘message’: ‘Connecting to Polygon’, ‘status’: ‘connecting’})
2020-06-23 04:28:44.060167   debug:  Entity({‘ev’: ‘status’, ‘message’: ‘Connected Successfully’, ‘status’: ‘connected’})
2020-06-23 04:28:44.200134   debug:  Entity({‘ev’: ‘status’, ‘message’: ‘authenticated’, ‘status’: ‘auth_success’})
2020-06-23 04:28:44.250377   debug:  Entity({‘ev’: ‘status’, ‘message’: ‘subscribed to: Q.’, ‘status’: ‘success’})
2020-06-23 04:28:44.251205   debug:  Entity({‘ev’: ‘status’, ‘message’: 'subscribed to: T.’, ‘status’: ‘success’})
2020-06-23 04:28:44.253505   debug:  Entity({‘ev’: ‘status’, ‘message’: ‘subscribed to: AM.’, ‘status’: ‘success’})
2020-06-23 04:28:44.258159   debug:  Entity({‘ev’: ‘status’, ‘message’: 'subscribed to: A.’, ‘status’: ‘success’})
A      2020-06-23  AAL            0.00%    14.41    14.41  158
A      2020-06-23  BA             0.00%   191.20   191.25  300
A      2020-06-23  GLD            0.00%   165.19   165.19  800
A      2020-06-23  KTOV           0.00%     0.94     0.94  100
A      2020-06-23  IDEX           0.00%     3.65     3.65  260
Here is broken output using api version 0.48:
( pip3 install alpaca_trade_api==0.48 )
unknown channel A.* (you may need to specify the right data_stream)
ERROR:asyncio:Task was destroyed but it is pending!
task: <Task pending name=‘Task-1’ coro=<reloadWatch..watch_command() running at simpleStream.py:96> wait_for=<Future pending cb=[<TaskWakeupMethWrapper object at 0x7f16f48aa460>()]>>
