Hi @Stadou
This might be an issue with the API itself. In my case, it only returns data for certain user IDs, but for most user IDs, it returns a 404 error, even though these user IDs do exist in the list.
I recommend opening a support ticket with the Microsoft support team to understand the cause of the error. Alternatively, you can click the "feedback" button on the documentation to report the issue.
As a workaround, you can try using the $filter
query parameter and the UPN attribute to filter the list set to retrieve the registration details for specific users.
https://graph.microsoft.com/v1.0/reports/authenticationMethods/userRegistrationDetails?$filter=userPrincipalName eq '{UPN}'
Hope this helps.
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