Request Id: dee1bff4-7c0b-402f-a1ba-552fc0f73800 Correlation Id: f598c17d-e9c2-4999-b761-216644905986 Timestamp: 2026-07-28T16:14:22Z Message: AADSTS900561: The endpoint only accepts POST requests. Received a GET request.

AADSTS900561 means the authentication flow sent a GET request to an endpoint that only accepts POST requests.

For Microsoft Entra authentication flows, the token exchange must be a POST request to the token endpoint. In an OAuth 2.0 authorization code flow, the app first gets an authorization code, then must redeem that code by sending a POST request to the token endpoint with the required parameters.

If this is happening in a browser sign-in scenario, common causes include a broken sign-in session, stale cookies, blocked third-party cookies, or browser extensions interfering with authentication. Try these steps:

1. Sign out completely, close all browser tabs, and start a new sign-in session.
2. Try an InPrivate/Incognito window.
3. Clear browser cache and cookies.
4. Allow third-party cookies.
   • In Edge: Settings > Privacy, search, and services > Cookies > turn off Block third-party cookies.
   • In Chrome: Settings > Privacy and security > Third-party cookies > select Allow third-party cookies.
5. Temporarily disable privacy/ad-blocking browser extensions.
6. If the issue is app-based rather than browser-based, verify the app is exchanging the authorization code for a token by sending a POST request to the token endpoint, not a GET request.

If the error is coming from a custom or third-party application, the application owner needs to correct the authentication flow so the code redemption step uses POST.

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