AADSTS900561: Resolving Endpoint Request Method Errors

The error AADSTS900561 occurs when a web request is made using the GET method instead of the POST method. This typically happens during authentication processes, where the endpoint is configured to accept only POST requests for security reasons. When a GET request is sent instead, the server rejects it, resulting in this error.

Understanding the Error

The error message “AADSTS900561: The endpoint only accepts POST requests. Received a GET request” indicates a mismatch between the type of HTTP request expected by the server and the type of request actually sent by the client.

Technical Aspects:

1. HTTP Methods:

   • GET Request:
     • Purpose: Retrieve data from a server.
     • Characteristics:
       • Data is sent in the URL.
       • Typically used for fetching resources.
       • Idempotent (multiple identical requests have the same effect as a single request).
     • Example: GET /api/resource?id=123
   • POST Request:
     • Purpose: Submit data to be processed to a server.
     • Characteristics:
       • Data is sent in the request body.
       • Used for creating or updating resources.
       • Not idempotent (multiple identical requests can have different effects).
     • Example: POST /api/resource with JSON body { "name": "example" }

2. Error Context:

   • The server endpoint is configured to handle only POST requests.
   • A GET request was sent instead, causing the server to reject it with the AADSTS900561 error.

Why This Happens:

• Misconfiguration: The client application might be incorrectly configured to send a GET request instead of a POST request.
• Browser Issues: Sometimes, browser settings or extensions can alter the type of request being sent.
• Code Errors: The code making the request might have a bug or incorrect logic.

Resolution:

• Check Request Method: Ensure the client application is sending a POST request to the endpoint.
• Browser Settings: Verify that browser settings or extensions are not interfering with the request type.
• Code Review: Inspect the code to confirm it correctly specifies a POST request where needed.

Common Causes

Here are some common scenarios that can lead to the ‘AADSTS900561: The endpoint only accepts POST requests. Received a GET request’ error:

1. Incorrect URL Usage: This error often occurs when the URL intended for a POST request is mistakenly used in a GET request. For example, using a browser to access an endpoint that should only be accessed programmatically via POST.

2. Misconfigured Settings: Misconfigurations in the application settings, such as incorrect endpoint URLs or HTTP methods, can trigger this error. Ensure that the application is configured to send POST requests to the correct endpoint.

3. Third-Party Cookies: Blocking third-party cookies in the browser can sometimes cause this error. Enabling third-party cookies or adding the endpoint to the list of trusted sites can help resolve this issue.

4. Browser Cache: Cached data in the browser might interfere with the request method. Clearing the browser cache can sometimes resolve this issue.

5. API Misuse: When using APIs like Microsoft Graph, ensure that the requests are correctly formatted and use the appropriate HTTP methods. For instance, attempting to fetch a token with a GET request instead of a POST request can lead to this error.

Troubleshooting Steps

Sure, here’s a step-by-step guide to troubleshoot and resolve the ‘AADSTS900561: The endpoint only accepts POST requests. Received a GET request’ error:

1. Check the Request Method:

   • Ensure that your application is sending a POST request to the endpoint. This error occurs when a GET request is sent instead of a POST request.

2. Review the Endpoint URL:

   • Verify that the URL you are using is correct and intended for POST requests. Double-check for any typos or incorrect paths.

3. Inspect Browser Settings:

   • Clear Cache and Cookies: Sometimes, cached data can cause issues. Clear your browser’s cache and cookies.
   • Allow Third-Party Cookies: Ensure that third-party cookies are not blocked. In Chrome, go to Settings > Privacy and security > Cookies and other site data and allow third-party cookies.

4. Add Trusted Sites:

   • Add https://login.microsoftonline.com to your list of trusted sites.
   • In Chrome, go to Settings > Privacy and security > Site Settings > Cookies and site data > Sites that can always use cookies and add the URL.

5. Use Incognito/Private Mode:

   • Open your browser in Incognito/Private mode and try accessing the endpoint again. This can help bypass some browser-specific issues.

6. Check Application Code:

   • Review your application code to ensure that the request method is set to POST. Look for any hardcoded GET requests that might be causing the issue.

7. Update Browser:

   • Ensure that your browser is up to date. Sometimes, outdated browsers can cause unexpected issues.

8. Restart Device:

   • Restart your computer or device to clear any temporary issues that might be affecting the request.

9. Check for Recent Changes:

   • If the issue started recently, review any recent changes to your application or environment that might have affected the request method.

10. Contact Support:

    • If the issue persists, contact Microsoft support for further assistance. Provide them with detailed information about the error and the steps you have already taken.

Following these steps should help you resolve the ‘AADSTS900561′ error.

Preventive Measures

Here are some best practices to prevent the AADSTS900561: The endpoint only accepts POST requests. Received a GET request error:

1. Use Correct HTTP Methods: Ensure your application uses POST requests for endpoints that require them.
2. Validate Endpoints: Double-check that your API endpoints are correctly configured to accept POST requests.
3. Update API Calls: Review and update any API calls in your code to use POST instead of GET where necessary.
4. Check Middleware: Ensure any middleware or routing logic correctly handles and forwards POST requests.
5. Test Thoroughly: Implement comprehensive testing to catch incorrect HTTP methods before deployment.
6. Review Documentation: Regularly review API documentation for any changes in endpoint requirements.

Implementing these practices should help prevent this error in your future applications.

The Error AADSTS900561

The error AADSTS900561 occurs when a GET request is sent to an endpoint that only accepts POST requests, typically during authentication processes.

This happens due to misconfiguration, browser issues, or code errors. To resolve this issue, check the request method, review the endpoint URL, inspect browser settings, and update application code to ensure it correctly specifies a POST request where needed.

Prevention Strategies

• Use correct HTTP methods
• Validate endpoints
• Update API calls
• Check middleware
• Test thoroughly
• Review documentation

By following these strategies, you can prevent this error in future applications and ensure a smooth authentication process.