数据下载失败，触发异常：
Traceback (most recent call last):
File "D:\veighna_studio\lib\site-packages\vnpy_ctabacktester\engine.py", line 404, in run_downloading
data: List[BarData] = self.datafeed.query_bar_history(req)
File "D:\veighna_studio\lib\site-packages\vnpy_rqdata\rqdata_datafeed.py", line 144, in query_bar_history
rq_symbol: str = to_rq_symbol(symbol, exchange)
File "D:\veighna_studio\lib\site-packages\vnpy_rqdata\rqdata_datafeed.py", line 36, in to_rq_symbol
if exchange in [Exchange.SSE, Exchange.SZSE]:
File "D:\veighna_studio\lib\enum.py", line 437, in getattr
raise AttributeError(name) from None
AttributeError: SSE

今天早上整个升级过一次系统，vnpystation 版本号 3.4.0，不知道 和这个升级有没有关系，哪位大佬帮忙解答一下，不胜感激~

这里的报错来自于常量定义里面的Enum模块，似乎这个Exchange枚举值常量被破坏了，卸载重装vnpy试试吧：

pip uninstall vnpy -y
pip install vnpy==3.4.0