Accessing the http error object in web api client

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web

API

I have created as web api HttpResponseMessage with http error object.
Ex:actionExecutedContext.Request.CreateErrorResponse(HttpStatusCode.Unauthorized, new HttpError { ExceptionType = "102", ExceptionMessage = "Unathorized Exception", Message = actionExecutedContext.Exception.Data["ActivityID"].ToString() });

now I need to access the http error object in web api client. for that I have created a class
public class ErrorDetails
{
public string ExceptionMessage { get; set; }
public string ExceptionType { get; set; }
public string Message { get; set; }
public string StackTrace { get; set; }
}

var error = response.Content.ReadAsAsync<errordetails>().Result;

when I try to deserialize the error object like above. getting an Aggregate exception.

Can any one help me on this. I need to access the error object
like ex : error.Exceptionmessage