Support Request: Unable to Use makeEwsRequestAsync Due to Security Defaults / Token Retrieval Blocked

Question

We are developing an Outlook Web Add-in that uses Office.context.mailbox.makeEwsRequestAsync to perform EWS operations. However, when attempting to use this method, we receive the following Internal Server Error:

"Token retrieval is not supported for this organization. Contact your administrator for assistance. Error ID = 'A95FD8C9-FA9D-486B-819F-AD43695F8402'."

Upon checking our Azure AD configuration, we noticed that Security Defaults are enabled, which enforces modern authentication and blocks basic authentication.

Issue Details:

We believe this issue started within the past month. Previously, the same code using makeEwsRequestAsync was working fine. We would like to understand what might have changed recently to cause this issue.

Answer 1

Hi YKWong,

Thank you for posting your question in the Microsoft Q&A forum.

Begin in early January 2023, Microsoft permanently turns off Basic auth for multiple protocols for many Exchange Online tenants. So basic authentication should also be disabled early in your organization.

Starting February 2025, Microsoft begin to turn off legacy Exchange user identity and callback tokens for Exchange Online tenants. Maybe your makeEwsRequestAsync issue is related to legacy Exchange online tokens.

For your reference: Use Exchange Web Services (EWS) from an Outlook add-in - Office Add-ins | Microsoft Learn 

You can try to turn on to legacy Exchange online tokens and check if the add-in works again:

Turn legacy Exchange Online tokens on or off - Office Add-ins | Microsoft Learn 

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