jQuery Ajax call No element found issue

I am getting a javascript error on firefox 3.5, when trying to call an ajax method.

Please find the error below:

XML Parsing Error: no element found Location: moz-nullprincipal:{1a2c8133-f48f-4707-90f3-1a2b2f2d62e2} Line Number 1, Column 1:

^

this is my javascript function:

function Update(Id) {
    $.ajax({
        type: "GET",
        url: ROOT_URL + "/sevice/udates.svc/Update?Id=" + Id,
        success: function(response) {

        },
        async: false
    });
}