Azure Analysis Service Rest API Error - Status 400 (Bad Request) with "unauthorized" message

I am trying to call the Azure Analysis Service API, to refresh my model, using this documentation as a reference, (https://learn.microsoft.com/en-us/azure/analysis-services/analysis-services-async-refresh#post-refreshes) and I'm getting this error:

{
    "code": "Unauthorized",
    "subCode": 0,
    "message": "An internal error occurred.",
    "timeStamp": "2021-06-09T16:04:46.0645307Z",
    "httpStatusCode": 400,
    "details": [
        {
            "code": "RootActivityId",
            "message": "f2f92034-12f2-4dac-8910-db89797150f6"
        },
        {
            "code": "Param1",
            "message": "asazure://asazureeus22-aspaaseastus2.asazure.windows.net/...."
        }
    ]
}

As you can see, the StatusCode is 400 (Bad Request), although the error message is unauthorized.

If, for example, a change the token that I'm using to an invalid one, I receive this message, with statusCode 401. (which makes sense)

{
    "code": "Unauthorized",
    "subCode": 0,
    "message": "Authentication failed.",
    "timeStamp": "2021-06-09T16:09:52.682502Z",
    "httpStatusCode": 401,
    "details": [
        {
            "code": "RootActivityId",
            "message": "8755550d-caf8-4789-91a4-2a4f567c9dd0"
        }
    ]
}

So, I believe that my token is valid, but something wrong is happening "inside" the AAS.

Can anyone help me to identify what exactly is this error?

Thank you.

Solution

This error occurs when the user (or service principal) does not have a server admin role on the Analysis Service.

So I add my service principal as Analysis Services Admins, and it is working now!