Callback Method Errors from AJAX Web Services
As I mentioned before, AJAX supports calling web services from the client using an XmlHttpRequest object. But sometimes, things don't go as expected. If you make the call, an error may occur in the web service, which you'd get an error prompt. However, there's one other aspect to this.
Sometimes the web service works fine, but you get an error with the breakpoint in the executor of the web service (ASP.NET AJAX code). There isn't a callstack, which is really hard to debug. What I've been finding out is that an error in the success or failed callbacks (which every web service supports a success or failed callback method that returns the results) will also act as if the executor failed, but that isn't the case.