笨办法学python3 习题20 报错UnicodeDecodeError: 'gbk' codec can't decode byte 0xff in position 0: illegal

笨办法学python3
笨办法学python3 习题20 报错UnicodeDecodeError: 'gbk' codec can't decode byte 0xff in position 0: illegal

报错如下
Traceback (most recent call last):
File “ex20.py”, line 18, in
print_all(current_file)
File “ex20.py”, line 6, in print_all
print(f.read())
UnicodeDecodeError: ‘gbk’ codec can’t decode byte 0xff in position 0: illegal multibyte sequence

python3.6.1版本,这个问题困扰我好久了
求大佬解惑,谢谢