As of today Alpaca removed the following fields from their API:

pattern_day_trader
daytrade_count
last_daytrade_count
daytrading_buying_power
last_daytrading_buying_power

 

This change causes live deployments to the Alpaca brokerages to fail, with new deployments returning the error:

Runtime Error:

During the algorithm initialization, the following exception has occurred: Error getting cash balance from brokerage: Required property 'pattern_day_trader' not found in JSON. Path '', line 1, position 950.Required property 'pattern_day_trader' not found in JSON. Path '', line 1, position 950. in HttpResponseMethodExtensions.cs:line 22 Required property 'pattern_day_trader' not found in JSON. Path '', line 1, position 950.  

 

Until QuantConnect removes calls for these fields from the backend, it does not appear to be possible to deploy live algorithms using the Alpaca brokerage.