UnicodeDecodeError: Invalid Start Byte

Why This Happens

Python 3 defaults to UTF-8. If the file uses Latin-1, Windows-1252, or is binary, the UTF-8 decoder encounters invalid bytes. You need to specify the correct encoding.

The Problem

with open('data.csv') as f:
    content = f.read()

The Fix

with open('data.csv', encoding='latin-1') as f:
    content = f.read()

# Or detect encoding:
import chardet
with open('data.csv', 'rb') as f:
    encoding = chardet.detect(f.read())['encoding']
with open('data.csv', encoding=encoding) as f:
    content = f.read()

Step-by-Step Fix

1. 1

   Try common encodings

   Try encoding='latin-1' or encoding='cp1252'.

2. 2

   Detect encoding

   Use chardet library to detect automatically.

3. 3

   Use errors parameter

   Open with errors='replace' or errors='ignore'.