jQuery 1.5 AJAX call fails with “invalid label” fo

Question

I've just upgraded from version 1.4 to version 1.5 of jQuery, and now my AJAX calls always fail with the "invalid label" error.

An example request is:

jQuery.ajax({
    async: false
    , dataType: "json"
    , error: function (xhr, status, error) { ... }
    , success: function (data, status, xhr) { ... }
    , type: "post"
    , url: "ajax/request.asp"
});

On the net I found this error is raised when the returned JSON is not wrapped with jQuery's callback (e.g. jQuery1234({ "something": "abcd" }).

The problem is I'm returning a JSON, not a JSONP (and I state it in the AJAX request), so why I must specify a callback in the returned JSON?

The 1.5 changelog says nothing about this... (Or it's me who can't read?)

Update:

This is an example of a not working JSON:

{
   "esito":"Ok",
   "centriCosto":[
      {
         "id":"1",
         "descrizione":"Colazione"
      },
      {
         "id":"2",
         "descrizione":"Pranzo"
      },
      {
         "id":"3",
         "descrizione":"Cena"
      }
   ]
}

And this is the same callback-wrapped working JSON:

jQuery1502710949228847014_1296739130498({
   "esito":"Ok",
   "centriCosto":[
      {
         "id":"1",
         "descrizione":"Colazione"
      },
      {
         "id":"2",
         "descrizione":"Pranzo"
      },
      {
         "id":"3",
         "descrizione":"Cena"
      }
   ]
})

By the way, Firebug says both of them are valid JSONs (and he's very picky about correctness).

Answer 1

looks like this is fixed now in v1.6 - had the same issue after upgrading to ver 1.5.1 & after upgrading to 1.6 the issue disappeared.

Answer 2

Here's the solution:

$.post("...", {},
        function(data) {

      // dont forget to add below lines         

         },"json");