Error message wrong???

[Transylvania]

First of all, my English is poor. So please forgive me.

I was coding with python3. Specific version → Python 3.7.0 (v3.7.0:1bf9cc5093, Jun 27 2018, 04:59:51) [MSC v.1914 64 bit (AMD64)] on win32
when I used 'urllib.parse.unquote' to unquote data, it throw a exception like this:

Error:
Error:
Traceback (most recent call last):
  File "<pyshell#3>", line 1, in <module>
    parse.unquote(bytes_test)
  File "D:\Python3\lib\urllib\parse.py", line 609, in unquote
    if '%' not in string:
TypeError: a bytes-like object is required, not 'str'

In my understanding, this message told me: "I need a 'bytes-like object' but you give me a 'str'. So it's wrong."
So I tried to make the variable to 'bytes-like object', but it did not work.
In the end, I found that this function actually needed a 'str' but not a 'bytes-like object'.
Is this error message wrong? Or I just misunderstand what it means.