error UnicodeDecodeError: 'utf-8' codec can't decode byte 0xff in position 0: invalid start byte

Question

Python tries to convert a byte-array (a bytes which it assumes to be a utf-8-encoded string) to a unicode string (str). This process of course is a decoding according to utf-8 rules. When it tries this, it encounters a byte sequence which is not allowed in utf-8-encoded strings (namely this 0xff at position 0).

Since you did not provide any code we could look at, we only could guess on the rest.

From the stack trace we can assume that the triggering action was the reading from a file (contents = open(path).read()). I propose to recode this in a fashion like this:

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

That b in the mode specifier in the open() states that the file shall be treated as binary, so contents will remain a bytes. No decoding attempt will happen this way.

Use this solution it will strip out (ignore) the characters and return the string without them. Only use this if your need is to strip them not convert them.

with open(path, encoding="utf8", errors='ignore') as f:

Using errors='ignore' You'll just lose some characters. but if your don't care about them as they seem to be extra characters originating from a the bad formatting and programming of the clients connecting to my socket server. Then its a easy direct solution. reference

Use encoding format ISO-8859-1 to solve the issue.

Had an issue similar to this, Ended up using UTF-16 to decode. my code is below.

with open(path_to_file,'rb') as f:
    contents = f.read()
contents = contents.rstrip("\n").decode("utf-16")
contents = contents.split("\r\n")

this would take the file contents as an import, but it would return the code in UTF format. from there it would be decoded and seperated by lines.

I've come across this thread when suffering the same error, after doing some research I can confirm, this is an error that happens when you try to decode a UTF-16 file with UTF-8.

With UTF-16 the first characther (2 bytes in UTF-16) is a Byte Order Mark (BOM), which is used as a decoding hint and doesn't appear as a character in the decoded string. This means the first byte will be either FE or FF and the second, the other.

Heavily edited after I found out the real answer

This is due to the different encoding method when read the file. In python, it defaultly encode the data with unicode. However, it may not works in various platforms.

I propose an encoding method which can help you solve this if 'utf-8' not works.

with open(path, newline='', encoding='cp1252') as csvfile:
    reader = csv.reader(csvfile)

It should works if you change the encoding method here. Also, you can find other encoding method here standard-encodings , if above doesn't work for you.

use only

base64.b64decode(a) 

instead of

base64.b64decode(a).decode('utf-8')