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Fix OAuth Client Scope Error with SharePoint Sites.ReadWrite.All in FastAPI

Elise Williams Sep 27, 2026 870 views

Question details

The user is experiencing an authentication failure during the fetch_token step in a FastAPI backend when requesting specific SharePoint OAuth scopes.

How to Fix OAuth Client Scope Error with SharePoint Sites.ReadWrite.All in FastAPI

Product: SharePoint API
Device & OS: not provided
Scenario: Implementing an authorization-code flow in a FastAPI backend using requests-oauthlib to access SharePoint data.
Observed behavior: The fetch_token process fails when Sites.ReadWrite.All and offline_access scopes are requested, but succeeds when they are removed, even though a similar OneDrive integration works.

Before you start

Before troubleshooting the code, log into the Azure Portal (Microsoft Entra ID) to ensure that the Sites.ReadWrite.All permission has been added to your App Registration and that admin consent has been fully granted.

Solution 1Recommended

Verify Entra ID App Permissions and Consult Microsoft Q&A

Because this is a specialized development issue involving customized FastAPI OAuth integration and Microsoft Graph/SharePoint permissions, verifying your Azure app configuration and seeking help from Microsoft Developer support is the best approach.

Scope errors during fetch_token in the authorization-code flow typically indicate a mismatch between the scopes requested in your application code and the API permissions configured in your Microsoft Entra ID (formerly Azure AD) App Registration.

When dealing with broad SharePoint scopes like Sites.ReadWrite.All, tenant administrator consent is almost always required. If resolving app permissions does not fix the issue, you should escalate the problem to Microsoft's dedicated SharePoint developer community.

Verify API Permissions in Azure Portal

Log into the Azure Portal, navigate to Microsoft Entra ID > App registrations, and select your application. Under 'API permissions', ensure that 'Sites.ReadWrite.All' and 'offline_access' are explicitly added.

Grant Admin Consent

Check the status column next to your permissions. If a green checkmark is missing, click the 'Grant admin consent for [Your Tenant]' button. You must have administrator privileges to do this.

Prepare Troubleshooting Information

Gather your complete authorization URL, the exact token request, your configured redirect URIs, the tenant type (common, organizations, or specific tenant ID), and the exact scope-change error output.

Redact Sensitive Data

Before sharing your logs, strictly remove any client secrets, client credentials, and authorization codes from your request headers or bodies to protect your application.

Post on Microsoft Q&A

Visit the SharePoint Development section of Microsoft Q&A (https://learn.microsoft.com/en-us/answers/topics/382862/sharepoint-dev.html) and post your detailed issue along with the gathered configuration parameters for specialized assistance.

Verify Entra ID App Permissions and Consult Microsoft Q&A

Check Microsoft Graph Formatting: Ensure that your requested scope strings in requests-oauthlib correctly reference the Microsoft Graph API resource URL (e.g., 'https://graph.microsoft.com/Sites.ReadWrite.All') if required by your tenant configuration.

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Frequently Asked Questions

Why does removing Sites.ReadWrite.All allow my FastAPI OAuth flow to succeed?

Removing this scope likely allows authentication to succeed because the remaining scopes (like basic profile or user read) do not require admin consent, whereas Sites.ReadWrite.All triggers stricter security policies in Entra ID that block the token fetch if consent is missing.

Do I need admin consent for SharePoint offline_access and Sites.ReadWrite.All?

Yes, broad permissions such as Sites.ReadWrite.All generally require a tenant administrator to explicitly grant admin consent in the Azure Portal before users can successfully authenticate and fetch tokens.

Why does my OneDrive integration work but SharePoint fails in the same FastAPI app?

OneDrive often relies on user-delegated Files.ReadWrite permissions which usually do not require admin consent. In contrast, SharePoint site-level permissions are broader and have stricter governance, often requiring admin approval.

How do I correctly format the scope string in requests-oauthlib for Microsoft APIs?

Ensure your scopes are separated by spaces. Depending on your endpoint (v1 vs v2), you may also need to prefix the scope with the resource URI, such as 'https://graph.microsoft.com/Sites.ReadWrite.All offline_access'.

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