Power BI REST API gives 403 error (User does not have access to group)

Using the following code:

System.Net.WebException ex;



Stream stream = ((System.Net.HttpWebResponse)(ex).Response).GetResponseStream();
using (StreamReader sr = new StreamReader(stream))
{
     string text = sr.ReadToEnd();
}

I was able to extract more detailed error information from the exception:

{"error":
{"code":"Unauthorized","message":"User(<ii>76e423fd-314d-42ff-ab23-306f25c46aea</ii>) does not have access to Group(<ii>2c6f2b64-162d-40c8-934e-44e3075c5ee8</ii>) with Permissions(ReadWrite)"}
}