Permission & Access Issues

Fix SharePoint Python Authentication HTTP 403 Forbidden Error

WPS Editor Oct 9, 2026 869 views

Question details

The user needs to resolve an HTTP 403 Forbidden error that occurs when authenticating to SharePoint using a Python script and Azure app registrations.

How to Fix SharePoint Python Authentication HTTP 403 Forbidden Errors

Product: SharePoint
Device & OS: not provided
Scenario: Attempting to access SharePoint resources programmatically using Python, Sites.Selected permissions, client secrets, or certificates.
Observed behavior: The server denies access and returns an HTTP 403 Forbidden error despite the authentication configuration.

Before you start

Ensure you have administrative access to the Azure Active Directory portal and the target SharePoint site administrator credentials to verify application permissions.

Solution 1Recommended

Verify Azure App Registration and API Permissions

Check if the Azure application has the correct Microsoft Graph or SharePoint API permissions and that tenant-wide admin consent has been granted.

HTTP 403 errors typically mean the authentication token was accepted, but the application lacks the required authorization to perform the requested action on the SharePoint site.

Open Azure Portal

Log into the Azure Portal and navigate to Azure Active Directory > App registrations, then select your application.

Check API Permissions

Click on 'API permissions' in the left menu. Ensure that 'Sites.Selected' or the appropriate Microsoft Graph/SharePoint API permissions are correctly added to the list.

Grant Admin Consent

Verify that there is a green checkmark indicating tenant-wide admin consent has been granted. If not, click 'Grant admin consent for [Your Tenant]'.

Validate Certificates and Secrets

Navigate to 'Certificates & secrets' and confirm that the client secret or certificate used in your Python script is currently valid and has not expired.

Verify Azure App Registration and API Permissions

Sites.Selected Configuration: If using 'Sites.Selected', remember that adding the permission in Azure AD is not enough. You must also grant the specific app access to the specific SharePoint site using a Microsoft Graph POST request.

Solution 2

Seek Developer Support on Microsoft Q&A

Since Python authentication involves complex code and tenant-specific configurations, consulting Microsoft experts is recommended for in-depth analysis.

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Frequently Asked Questions

What does an HTTP 403 Forbidden error mean in the context of the SharePoint API?

An HTTP 403 error indicates that the server understands your Python request and recognizes your authentication token, but refuses to authorize the action. This usually points to missing API permissions, lack of admin consent, or incorrect site-level access roles.

How do I grant 'Sites.Selected' permissions to a specific SharePoint site?

You cannot configure this directly through the Azure or SharePoint UI. You must use the Microsoft Graph API to send a POST request to the specific site's permission endpoint, explicitly granting your Azure application 'write' or 'read' access to that site.

Can an expired client secret cause a 403 Forbidden error?

Yes. If the client secret or certificate configured in your Azure app registration has expired, the token requested by your Python script will be invalid or lack the necessary claims, resulting in access being denied by SharePoint.

Which Python libraries are best for handling SharePoint and Azure authentication?

The official 'msal' (Microsoft Authentication Library) for Python is highly recommended for acquiring tokens from Azure AD. Additionally, the 'Office365-REST-Python-Client' library is widely used as it abstracts much of the API complexity when interacting with SharePoint.

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