Question

I have tried upgrading from jQuery 1.2.6 to 1.4.1.
A JSON query is now failing with error : “parseerror, invalid label”

I have simplified the code to bare minimum.

var jsonUrl = "process_01.php";
$.ajax({
 type: "POST",
 url:  jsonUrl,   
 data: "var=myVar",        
 dataType: "json",    
 beforeSend: function(msg) {
 },
 success: function(msg) {
 },
 error: function (msg, textStatus, errorThrown) {
   alert("an error has occured (" + textStatus + " " + errorThrown +")" );
   }
});
return false;
}

Output of php program is
{“foo”:”bar”,”IsTrue”:”true”}

I can see this in firebug

Answer 1

Make sure your content type is set to application/json.

Also look at this, looks similar to your problem.