jQuery $.ajax() function's error message

 $.ajax({
        type: "POST",
        url: "SOME_URL",
        data: JSON.stringify(data),
        dataType: "json",
       
        success: function(response) {
            alert("success");
        },
        error: function(xhr, ajaxOptions, thrownError) {
            alert('Error: ' + thrownError);
        }
    })