don't know which module to import (try placing a "module" or "currentmodule" directive in the document, or giving an explicit module name)

Question

I'm new to Sphinx and I'm using Sphinx's auto-generate tool. I was trying to import all methods in a class from a python folder. I successfully set the path in conf.py like this

import os
import sys

sys.path.insert(0, os.path.abspath(r'path'))

Here is how my auto generate code looks like :

.. autoclass:: nameofpythonfile
   :members: 

However, when I try to build the HTML using make HTML it gives me this error

Running Sphinx v4.0.2
loading pickled environment... done
building [mo]: targets for 0 po files that are out of date
building [html]: targets for 1 source files that are out of date
updating environment: 0 added, 1 changed, 0 removed
reading sources... [100%] code
WARNING: don't know which module to import for autodocumenting 'synthesizer' (try placing a "module" or "currentmodule" directive in the document, or giving an explicit module name)
looking for now-outdated files... none found
pickling environment... done
checking consistency... done
preparing documents... done
writing output... [100%] index
generating indices... genindex done
writing additional pages... search done
copying static files... done
copying extra files... done
dumping search index in English (code: en)... done
dumping object inventory... done
build succeeded, 1 warning.

The HTML pages are in build\html.