XHR failed loading: POST

XHR failed loading: POST

I am using Ajax to call a servlet which return a String message.
The servlet gets called successfully as I can see some println statements in my console.
But after that i get an error XHR failed loading: POST.

The code is -
xhttp.onreadystatechange = function() {
if (xhttp.readyState == 4 && xhttp.status == 200) {
var result = xhttp.responseText;
deleteItemsIDsResult(result);
}
};
xhttp.open("POST", "ItemsIDsDelServlet", true);
xhttp.setRequestHeader("Content-type","application/x-www-form-urlencoded");
xhttp.send(data);

The data send to the servlet is -

itemsToBeDeleted=df,dxffx,fxd,fxdxd,fxf,dxfd,,&region=swed&userid=edrf&pwd=rrff

Any leads please.

Thanks.