return b.decode("utf-8") UnicodeDecodeError: 'utf-8' codec can't decode byte 0xe9 in position 14: invalid continuation byte code example

Example: UnicodeDecodeError: 'utf-8' codec can't decode byte 0xe9 in position 2892: invalid continuation byte

As suggested by Mark Ransom, I found the right encoding for that problem.
The encoding was "ISO-8859-1", so replacing

open("u.item", encoding="utf-8")
with
open('u.item', encoding = "ISO-8859-1")

will solve the problem.