Backtrader - multiprocessing.pool.MaybeEncodingError: Error sending result

1. Error Message

multiprocessing.pool.MaybeEncodingError: Error sending result: '[<backtrader.cerebro.OptReturn object at 0x000002DF30503CF8>]'. Reason: 'PicklingError("Can't pickle <class 'backtrader.metabase.AutoInfoClass_7b18485c665643a9b59eb66411db33ad_2823.HK'>: attribute lookup AutoInfoClass_7b18485c665643a9b59eb66411db33ad_2823.HK on backtrader.metabase failed",)'

 

2. stdstats

cerebro = bt.Cerebro(stdstats=False)

　　按官方文档说，当加入其他Observers，便要stdstats=False，否则会引致错误

 

3. Official doc

https://www.backtrader.com/docu/observers-and-statistics/observers-and-statistics/