Use Python to call SharePoint API get 401 response while I have the token

I have registered my App in Azure with API permission as below:

Here is my python code.

import requests
from msal import ConfidentialClientApplication

client_id = "xxxxxxxxxxxxxxxxxxxxx"
client_secret = "yyyyyyyyyyyyyyyyyyyyy"
tenant_id = "tttttttttttttttttttttttttttttttttttttttt"
site_url = "https://{mytenent}.sharepoint.com/sites/mysite"
resource = "https://{mytenent}"

# Authenticate using client ID and secret
authority = f"https://login.microsoftonline.com/{tenant_id}"
app = ConfidentialClientApplication(
    client_id=client_id,
    authority=authority,
    client_credential=client_secret,
)

scope=[resource + "/.default"]
token_response = app.acquire_token_for_client(scopes=scope)


access_token = token_response.get("access_token") #token_response["access_token"]
print(access_token)

endpoint_url = f"{site_url}/_api/web"
headers = {
    "Authorization": "Bearer " + access_token,
    "Accept": "application/json;odata=verbose",
    "Content-Type": "application/json;odata=verbose",
}
print(endpoint_url)
response = requests.get(endpoint_url, headers=headers)

# Check for errors in the SharePoint API response
if response.status_code == 200:
    data = response.json()
    print("SharePoint Site Title:", data["d"]["Title"])
else:
    print("SharePoint API Error:")
    print("Status Code:", response.status_code)
    print("Response:", response.text)

By the code print(access_token) I can get the token string so I think I do it right on get a token. But I got 401 response when calling SharePoint API.

Status Code: 401 Response: {"error_description":"ID3035: The request was not valid or is malformed."}

What could be the problem? Thanks for your advice.

I registered one Entra ID application and granted API permissions as below:

Initially, I got same error when I ran your python code in my environment like this:

import requests
from msal import ConfidentialClientApplication

client_id = "xxxxxxxxxxxxxxxxxxxxx"
client_secret = "yyyyyyyyyyyyyyyyyyyyy"
tenant_id = "tttttttttttttttttttttttttttttttttttttttt"
site_url = "https://{mytenent}.sharepoint.com/sites/mysite"
resource = "https://{mytenent}"

# Authenticate using client ID and secret
authority = f"https://login.microsoftonline.com/{tenant_id}"
app = ConfidentialClientApplication(
    client_id=client_id,
    authority=authority,
    client_credential=client_secret,
)

scope=[resource + "/.default"]
token_response = app.acquire_token_for_client(scopes=scope)


access_token = token_response.get("access_token") #token_response["access_token"]
print(access_token)

endpoint_url = f"{site_url}/_api/web"
headers = {
    "Authorization": "Bearer " + access_token,
    "Accept": "application/json;odata=verbose",
    "Content-Type": "application/json;odata=verbose",
}
print(endpoint_url)
response = requests.get(endpoint_url, headers=headers)

# Check for errors in the SharePoint API response
if response.status_code == 200:
    data = response.json()
    print("SharePoint Site Title:", data["d"]["Title"])
else:
    print("SharePoint API Error:")
    print("Status Code:", response.status_code)
    print("Response:", response.text)

Response:

To resolve the error, you can switch to delegated flows like interactive flow, authorization code flow etc.. for generating token as you granted permissions of Delegated type.

In my case, I ran below modified code that uses interactive flow for generating token and got response successfully like this:

import requests
import msal

client_id = "appId"
tenant_id = "tenantId"
site_url = "https://tenant.sharepoint.com/sites/sridemosite"
resource = "https://tenant.sharepoint.com"

# Authenticate using client ID and secret
authority = f"https://login.microsoftonline.com/{tenant_id}"

app = msal.PublicClientApplication(
    client_id,
    authority=authority,
)
scope=[resource + "/.default"]
token_response = app.acquire_token_interactive(scopes=scope)
access_token = token_response['access_token']
print(access_token)

endpoint_url = f"{site_url}/_api/web"
headers = {
    "Authorization": "Bearer " + access_token,
    "Accept": "application/json;odata=verbose",
    "Content-Type": "application/json;odata=verbose",
}
print()
print(endpoint_url)
response = requests.get(endpoint_url, headers=headers)

# Check for errors in the SharePoint API response
if response.status_code == 200:
    data = response.json()
    print("SharePoint Site Title:", data["d"]["Title"])
else:
    print("SharePoint API Error:")
    print("Status Code:", response.status_code)
    print("Response:", response.text)

Response:

Make sure to enable public client flow and add redirect URI in Mobile and desktop applications platform while using interactive flow:

Alternatively, you can also generate access token using client certificate by granting permissions of Application type, refer below blog:

Getting an App Only access token for SharePoint REST APIs by Martin Loitzl