Fix: Server Unauthorized Scopes In Entra OAuth

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Understanding the 'Server Granted Unauthorized Scopes' Issue in Microsoft Entra OAuth

**Understanding the 'Server Granted Unauthorized Scopes' Issue in Microsoft Entra OAuth**

Hey guys! Let's dive into a common problem you might face when working with Microsoft Entra OAuth: the "Server granted unauthorized scopes" error. This issue pops up when the server, in this case, the MCP OpenAPI Proxy, receives a token with permissions (scopes) that it wasn't expecting or authorized to have. It's like the server is saying, "Hold on, these permissions don't match what I'm supposed to do!" This can happen for various reasons, and we'll break down the problem, the steps to reproduce it, and most importantly, how to fix it. This error prevents the application from starting successfully and throws an OAuthTokenError.

What Causes the Unauthorized Scopes Error?

So, what's going on under the hood? Essentially, during the OAuth flow, the client (your application) requests specific permissions (scopes) from the authorization server (Microsoft Entra ID). These scopes dictate what resources your application can access on behalf of the user. When the token is issued, the server checks if the requested scopes are allowed. If the token includes scopes that the server doesn't recognize or isn't configured to handle, this error surfaces. This often leads to failed connections and application startup issues.

Steps to Reproduce the Issue (and the Log Files)

The user's issue provides clear steps and log files. To reproduce this error, you would typically:

  1. Run the mcpo command: The user starts the MCP OpenAPI Proxy using the mcpo --config .\[config.json] command. This command starts the server using the configurations in the provided config.json file.
  2. Configuration: The config.json file is crucial here. It specifies the settings for the MCP Server, including the OAuth details such as the server URL.
  3. OAuth Flow Initiation: The logs show that the MCP Server initiates the OAuth flow by opening a browser window for authorization. It directs to the authorization endpoint (http://localhost:3000/authorize).
  4. Token Request and Error: The crucial part is when the application tries to get the token. The logs then display a 401 Unauthorized error, which is the immediate sign of an issue, along with an OAuthTokenError. The traceback clearly shows the Server granted unauthorized scopes error, followed by a list of unauthorized scopes. These scopes (like User.Read, Mail.ReadWrite, etc.) are the permissions the server received that it was not expecting or authorized to handle, leading to the failure.

Analyzing the Logs

The logs are a treasure trove of information! Here's what we can glean:

  • Server Startup: The server starts, loads the configuration, and attempts to connect to the test server.
  • OAuth Configuration: The system recognizes the OAuth configuration.
  • HTTP Requests: We can see HTTP requests to various endpoints for authentication, authorization, and token retrieval.
  • Error Messages: The ERROR logs are the key here. They indicate the OAuthTokenError and the list of unauthorized scopes. These messages are critical to pinpointing the root cause.
  • Configuration File: The config.json file is vital in this context, defining the server’s OAuth settings.

Troubleshooting and Solutions: Resolving Unauthorized Scopes

Alright, so how do we fix this? Here are the most common solutions and troubleshooting steps. Bear in mind, this is often a configuration issue, so double-check those settings!

1. Scope Validation and Configuration

  • Verify Scopes in Configuration: The primary step is to ensure that the scopes requested by your application align with the scopes the server expects. Check the configuration file (config.json in this case) to confirm that the scopes requested during the authorization flow match the scopes the server is designed to handle. This involves looking at the scope parameter in your authorization request.
  • Match Scopes: Make sure the requested scopes (e.g., User.Read.All, Mail.Read) are correctly listed. Any discrepancies here could cause authorization failures. The authorized scope should match with the scopes_supported in the /.well-known/oauth-authorization-server endpoint.
  • Example: In your config.json or the application's OAuth settings, review the scopes you're requesting. If you're only trying to read user profiles, you shouldn't be asking for Mail.ReadWrite or other unrelated scopes.

2. Check the Microsoft Entra Application Registration

  • Application Permissions: Go to the Azure portal and navigate to your application registration in Microsoft Entra ID. Here, verify the API permissions configured for your application. Make sure the requested scopes are correctly added and granted. This is the place where you define what permissions your application has.
  • Grant Admin Consent: Sometimes, you might need to grant admin consent for certain permissions. If you see a permission listed as