UnicodeEncodeError: 'charmap' codec can't encode character '\u0259' in position 44244: character maps to <undefined> code example

Example 1: charmap codec can't encode character

with open(filename_csv , 'w', newline='',encoding="utf-8") as csv_file:

Example 2: charmap' codec can't encode character '\u010d' in position 97: character maps to

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