Use fix_yahoo_Finance package, here provided pdr_override() can fix problems that cannot be read

from pandas_datareader import data as pdr

import fix_yahoo_finance as yf

yf.pdr_override()  # Used to fix, necessary

# Get data
data = pdr.get_data_yahoo("SPY", start="2017-01-01", end="2017-04-30")
# Print
print(data.head())