If I run a basic TWS example, I receive the error message . If I comment out the error() call back it runs fine. I've tried this on several examples and get the same result. Exception has occurred: TypeError error() takes 4 positional arguments but 5 were given File "/Users/jayurbain/Dropbox/twsapi/Algorithmic Trading using Interactive Broker's Python API /ib_basic_app.py", line 20, in <module> app.run() Please advise. Here's the call back that is being overridden in wrapper.py: def error(self, reqId:TickerId, errorCode:int, errorString:str, advancedOrderRejectJson = ""): Here is the entire code: from ibapi.client import EClient from ibapi.wrapper import EWrapper class TradingApp(EWrapper, EClient): def __init__(self): EClient.__init__(self,self) def error(self, reqId, errorCode, errorString): print("Error {} {} {}".format(reqId,errorCode,errorString)) app = TradingApp() app.connect("127.0.0.1", 7497, clientId=1) app.run() Continue reading...