Top 5 Answer for python - "for line in..." results in UnicodeDecodeError: 'utf-8' codec can't decode 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.
The following also worked for me. ISO 8859-1 is going to save a lot, mainly if using Speech Recognition APIs.