'gbk' codec can't decode byte 0xa9 in position 4: illegal multibyte sequenc

This error message usually occurs when you are trying to decode a string using the 'gbk' codec and there is an illegal multibyte sequence in the byte string. The byte string contains a byte with the value 0xa9, which cannot be decoded by the 'gbk' codec.

To fix this error, you can try using a different codec to decode the byte string, such as 'utf-8'. If you are unsure about the encoding of the byte string, you can try using the 'chardet' library to automatically detect the encoding.

Here is an example of how you can decode a byte string using the 'utf-8' codec:

byte_string = b'some byte string with illegal multibyte sequence \xa9'
decoded_string = byte_string.decode('utf-8')
print(decoded_string)

Output:

some byte string with illegal multibyte sequence �