AADSTS50011 – Microsoft Events OAuth redirect URI mismatch

Question

AADSTS50011 – Microsoft Events OAuth redirect URI mismatch

Event sign-in fails using Microsoft-owned AppId:

11a8fed6-60c9-42fa-aef8-7a18d34cf923

Redirect URI requested:

https://msevents.microsoft.com/event

Tenant not involved – issue reproduces across tenants.

Request ID: 7ca84d72-b14e-44e9-bb19-e26a8aab0600

Correlation ID: a7007626-23b8-4294-bda5-98cad345508e

Timestamp: 2026-01-19T14:39:34Z

Answer 1

Hi,
This is still an issue after a month. This has nothing to do with cache or cookies. It is a misconfiguration on MS side. Who can escalate this?
Thx,
István

Answer 2

Hi Shane Lackey,

I am following up to verify if the distinction regarding the First-Party Application ID provided the necessary clarity on this authentication failure. Since the AppId 11a8fed6-60c9-42fa-aef8-7a18d34cf923 is proprietary to the Microsoft Events platform, the AADSTS50011 mismatch is structurally impossible for a tenant administrator to resolve via Azure AD or Entra ID configurations. The error confirms that the redirect_uri being sent by the web application's frontend does not match the hardcoded allowlist managed exclusively by Microsoft's engineering team.

If attempting the sign-in process through an InPrivate or Incognito window to bypass local token caching did not resolve the loop, the issue is confirmed as a service-side regression. In this state, no changes to your local environment or tenant settings will correct the OAuth flow, and the resolution depends entirely on Microsoft correcting the Service Principal configuration on their backend.

If the issue has been successfully resolved, please consider accepting the answer as it helps other people sharing the same question benefit too. Thank you!

VP

Answer 3

Hello Shane Lackey,

This AADSTS50011 error is triggered because the authentication request generated by the website is passing https://msevents.microsoft.com/event as the redirect_uri parameter, but that specific URI is missing from the allowlist in Microsoft's master App Registration. Since this is a service-side misconfiguration on a Microsoft-owned endpoint, you cannot fix it via Azure PowerShell or the Portal.

Your primary recourse is to rule out client-side caching of a malformed authentication flow. Open an InPrivate or Incognito window and navigate directly to the root URL https://msevents.microsoft.com/ rather than a deep link or bookmarked URL. If the sign-in works there, the issue was a stale generic token or a bad link cached in your browser. If the error persists in a private window, this confirms a regression in the Microsoft Events production environment. In that case, because you cannot alter the OAuth2 configuration for a first-party app, you must wait for Microsoft engineering to correct the Service Principal configuration to match their frontend deployment.

I hope you've found something useful here. If it helps you get more insight into the issue, it's appreciated to accept the answer. Should you have more questions, feel free to leave a message. Have a nice day!

VP

Answer 4

The AADSTS50011 error indicates that the redirect URI specified in the request does not match any of the redirect URIs configured for the application. This can happen if the redirect URI is not properly registered in the app settings or if the application is using a different URI than what is registered.

To resolve this issue, ensure that the redirect URI you are using, https://msevents.microsoft.com/event, is correctly registered in the Azure app registration for the application with AppId 11a8fed6-60c9-42fa-aef8-7a18d34cf923. You can check the registered redirect URIs in the Azure portal under the app registration settings. If the URI is not listed, you will need to add it.

Additionally, it is a good practice to clean up any old or unused redirect URIs to avoid confusion and potential errors in the future.