jQuery AJAX JSON parseerror

I've got a webpage with an AJAX request using jQuery and dataType=json

$.ajax({
 type: "POST",
 url: 'api/',
 data: post,
 success: function(data) {}
 dataType: 'json',
 error: function(jqXHR, textStatus, errorThrown) {
  var message = myprint(errorThrown)+myprint(textStatus)+myprint(jqXHR);
  // myprint is a custom print function
  alert(message);
 }
}

About 1% of the time, I got this alert :

{}
"parsererror"
{
 "readyState": 4,
 "responseText": "{\"results\":[\"TEST1\",\"TEST2\"],\"time\":\"0,123\"}",
 "status": 200,
 "statusText": "OK"
}

Clearly there is no parseerror. Do you have any idea that I might check ? Thank you.

Error: "showing-json parse error" that mean: data format response from server incorrect.

In client, you set dataType is 'json' but into data response is not json data or may be xml (i not sure, you should check again).