代码很简单，我不知道如何解决这个错误。所有软件包都已更新。

import datetime as dt
import yfinance as yf

ticker = 'MSFT'
start_date = dt.datetime(2020,1,1)

data = yf.download(ticker, start_date)

错误在.json中，我不知道如何解决这个问题。

Exception in thread Thread-1:
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/threading.py", line 954, in _bootstrap_inner
    self.run()
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/threading.py", line 892, in run
    self._target(*self._args,**self._kwargs)
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/multitasking/__init__.py", line 102, in _run_via_pool
    return callee(*args,**kwargs)
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/yfinance/multi.py", line 169, in _download_one_threaded
    data = _download_one(ticker, start, end, auto_adjust, back_adjust,
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/yfinance/multi.py", line 181, in _download_one
    return Ticker(ticker).history(period=period, interval=interval,
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/yfinance/base.py", line 157, in history
    data = data.json()
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/requests/models.py", line 900, in json
    return complexjson.loads(self.text,**kwargs)
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/json/__init__.py", line 346, in loads
    return _default_decoder.decode(s)
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/json/decoder.py", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/json/decoder.py", line 355, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)