why does the 'error' function of $.ajax execute even when the request to invoke a webmethod succeeds?

Question

hi, I am using jquery ajax method to invoke a webmethod upon clicking a 'span'.This is webmethod is in one of my aspx pages and I am invoking it from the master page using the following code.

 $(document).ready(function(){
     $("#btn").click(function() {
        $.ajax({   
              type: "POST", 
              url: "Default.aspx/removedata",
              data:"{}",
              contentType: "application/json; charset=utf-8",
              dataType: "json",  
              success:function(msg) {  
                   $("li#search").removeClass('current');
                   $("li#search").addClass('hide');
                   $("#tabnew").addClass('hide');
                   window.location="Result.aspx";       
              },
              error:function(xhr, status, error) {
                  alert("error");                       
                  //var err = eval("(" + xhr.responseText + ")");
                  // Display the specific error raised by the server 
                  //alert(err.Message);
                  console.log(xhr.statusText);
              }
          });
       });
    });

when I click the span I can see the webmethod getting invoked(by debugging ),but even before the webmethod starts executing I get the alert 'error' and I see (an empty string) message being logged into the firebug console. As far as I know the 'error' function gets executed only if the ajax request fails.But I can see the webmethod getting executed.I do not understand why the error function is executing even then.

Could someone please help me with this.

Thanks

Answer 1

The error handler is executed if the server side script returns an error code different than 200. You could use FireBug to inspect what exactly is happening under the covers.