Ajax呼叫-12019错误

We have ajax call in our application like below. It will be called for every left menu click. But sometimes we are getting 12019 error. We are unable to find any other error details. Just we are getting 'xhr.status' as 12019.

$.ajax({

    type : 'POST',
    url : requestURI,
    cache : false,
    data : formData,
    success : function(data) {
        $('#centerContentModel').html(data);
        ShowLayer();
    },
    error : function (xhr, errorType, thrownError) {
        alert("Status : "+xhr.status+" :: StatusText : " + xhr.statusText +" :: ErrorType : " + errorType);
        window.location.href="/https/ask.csdn.net/timeout.jsp";
    }

Anyone has any idea on this?