ext-base.js:21 POST [url]http://site.ru/connector.php[/url] 502 (Bad Gateway)

i @ ext-base.js:21
request @ ext-base.js:21
request @ ext-all.js:21
request @ modx.js?v=065c0bd8:503
_import @ import.panel.js:665
fn @ import.panel.js:685
_runCallback @ modx.js?v=065c0bd8:518
success @ modx.js?v=065c0bd8:477
handleResponse @ ext-all.js:21f @ ext-base.js:21
m @ ext-base.js:21
(anonymous function) @ ext-base.js:21

Ext.Ajax.request({
            url: ''
            , params: params
            , listeners: {
                'success': {
                    fn: function (e) {
                        console.log("success!!",e);
                    }, scope: this
                }
                , failure: {
                    fn: function (r) {
                        console.log("failure!!",r);
                       
                    }, scope: this
                }
            }
        });

Ext.Ajax.on({
   requestexception : function (ajax, xhr) {
      if (xhr.status == 502) console.log('OMG!);
   }
})

Ext.Ajax.request({
     url: 'ajax_demo/sample.json',
     success: function(response, opts) {
         var obj = Ext.decode(response.responseText);
         console.dir(obj);
     },
     failure: function(response, opts) {
         console.log('server-side failure with status code ' + response.status);
     },
    listeners: {
        requestexception: function (conn , response , options , eOpts) {

            ....

        }
    }
 });