Unable create subscriptions for Microsoft change notification

Question

Hi Team,

I am trying to create subscription for users change notification by sending POST request.
However, I keep getting below errors saying my request is invalid.
Previously, it worked as expected with same request params. (header and body).

Could you please help check and let me know if there is something wrong with my request? Thanks!

request Body:

{
    "changeType": "created",
    "notificationUrl": "https://axm-idp-notification-qa.apple.com/maid/v1/idp/ms",
    "resource": "users/",
    "expirationDateTime": "2023-08-11T06:06:17.141973Z",
    "clientState": "secretClientState"
}

Response

{
    "error": {
        "code": "InvalidRequest",
        "message": "The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.",
        "innerError": {
            "date": "2023-08-09T06:23:21",
            "request-id": "8a8c4fb0-fa5f-4074-b3b3-d7d39fd777ce",
            "client-request-id": "8a8c4fb0-fa5f-4074-b3b3-d7d39fd777ce"
        }
    }
}