This specific example would not work, since NUL bytes are not allowed in file names. open(b'test-\xd8\x01.txt', 'w').close() Makes the same point. Note t

This specific example would not work, since NUL bytes are not allowed in file names. open(b'test-\xd8\x01.txt', 'w').close() Makes the same point. Note that b'test-\xd8\x00.txt' is totally valid. You just can't use that as a file name.