Persistent 401 Unauthorized Error with Python API Keys Despite All Checks

Hello everyone,

I'm trying to use the official onshape-client library for Python to connect to the Onshape API, but I'm stuck on a persistent 401 Unauthorized error. My goal is simply to authenticate and eventually create a document, but I cannot get past the initial connection step.

I've followed all the standard troubleshooting steps but the server continues to reject my credentials. I'm hoping someone might have an idea what I could be missing.

What I've Already Tried

1. Set Correct Permissions: I have ensured the active keys have both Read and Write permissions enabled.
2. Confirmed My Base URL: My account is on the standard free plan and my browser URL is exactly https://cad.onshape.com. This is correctly set in my script.
3. Performed a "Clean" Copy/Paste: I've used the "Notepad Test" by pasting the keys into a plain text editor first before moving them to my script to ensure no hidden formatting characters are included.
4. Synced My System Clock: I have forced a sync of my Windows clock with the internet time server to ensure there is no time-skew issue.
5. Isolated the Problem: I am using a minimal test script (included below) that only attempts to authenticate and perform a single GET request.

Test Script

This is the exact code I am running. It uses debug logging to show the raw request details. Even with this script, the authentication fails.

Python

import logging

import sys

from onshape_client.client import Client

from onshape_client.oas.exceptions import ApiException



API_KEY    = "My_key"

API_SECRET = "My_key"

BASE_URL   = "https://cad.onshape.com"




def check_connection_with_debug():

    print("Attempting to connect with DEBUG LOGGING ENABLED...")

    logging.basicConfig(stream=sys.stdout, level=logging.DEBUG)


    client = Client(configuration={

        "base_url": BASE_URL,

        "api_key": API_KEY,

        "api_secret": API_SECRET

    })


    try:

        print("\n--- Performing test call to list documents ---")

        # A simple, read-only call to test the connection

        client.documents_api.get_documents(limit=1)


        print("\n" + "="*40)

        print("SUCCESS! Authentication is correct.")

        print("="*40 + "\n")


    except ApiException as e:

        print("\n" + "="*40)

        print(" FAILED! Authentication was rejected by the server.")

        print(f"This was a {e.status} error. See the log above for details.")


        print("="*40 + "\n")


if __name__ == '__main__':

    if "PASTE_YOUR" in API_KEY or "PASTE_YOUR" in API_SECRET:

        print("ERROR: You have not replaced the placeholder API keys in the script.")

    else:

        check_connection_with_debug()

My Question

Even after all these steps, the script consistently fails with a 401 Unauthorized error.

Does anyone have any ideas for other things I could check? Is there any other system setting, account configuration, or network issue that could lead to a valid API key being rejected?

Any help or suggestion would be greatly appreciated. Thank you!