Answers for "UnicodeEncodeError: 'charmap' codec can't encode characters in position 8862-8863: character maps to <undefined>"

charmap' codec can't encode character 'u010d' in position 97: character maps to <undefined>

import io
with io.open(fname, "w", encoding="utf-8") as f:
    f.write(html)

UnicodeDecodeError: 'charmap' codec can't decode byte 0x81 in position 92: character maps to <undefined>

file = open(filename, encoding="cp437")