Troubleshooting UnicodeDecodeError in Python's UTF-8 Decoding

Encountering the error "UnicodeDecodeError: 'utf-8' codec can't decode byte 0xff in position 0: invalid start byte" signifies that Python is attempting to decode a byte sequence using UTF-8 but encountering an invalid start byte. This occurs when a byte array, assumed to be a UTF-8-encoded string, contains characters outside the UTF-8 encoding規範。

Cause of the Error

In the provided example, opening a file using open(path).read() triggers the decoding attempt. Since the file contains bytes not conforming to UTF-8, the decoding process fails, resulting in the error.

Solution

To resolve this issue, it is imperative to handle the file as a binary instead of a text file. This prevents Python from attempting to decode the bytes as a UTF-8 string.

By modifying the code to open the file with the 'rb' mode, we force Python to read the file as a binary:

with open(path, 'rb') as f:
    contents = f.read()

Specifying the 'b' in the mode argument instructs Python to treat the file as a binary stream, ensuring that the contents remain a bytes object, without any decoding attempted.