Hi @Alberto Zumiani , what version are you using, 1.0 or beta? Have you changed anything recently like policies or subscription types? Is there any issue with your subscription? Have you followed and documents or threads to help resolve the issue? From the troubleshooting guide:
Based on an organization's CA policies, a user accessing Microsoft Graph resources via your app might be challenged for additional information that is not present in the access token your app originally acquired. In this case, your app receives a 400 with an interaction_required error during access token acquisition or a 403 with insufficient_claims error when calling Microsoft Graph. In both cases, the error response contains additional information that can be presented to the authorize endpoint to challenge the user for additional information (like multi-factor authentication or device enrollment).>
Since it has been working for months I don't think there's anything wrong with your implementation unless you recently changed or added something. Please let me know if anything above helps you. If not I will continue looking into this.
Thank you,
James