Sending base64 string to node.js from PhoneGap not working

Currently I am developing a PhoneGap app and for this I have got a small upload app method created, which will take the base64 string of the picture and send it to the server ( AJAX ). In the browser on my desktop everything goes good, no error and the data gets logged into the db, but when I am trying to do the same from my PhoneGap app something went wrong and I cannot call the methode.

The results of LogCat:

Unknown chromium error: -324

The source:

Client:

document.getElementById('btnReport').addEventListener('click', function (){
        api.upload(encodeURIComponent(image), location.coords.accuracy, location.coords.latitude, location.coords.longitude, location.timestamp, function (err, data){
          console.log("successful");
          alert("Your report was successful!");
        });
      });

Client side api:

this.upload = function (picture, accuracy, latitude, longitude, timestamp, callback) {
        //XMLHttpRequest
        var xhr = new XMLHttpRequest();
        //recieving response from the server asynchronoues
        xhr.open('GET', host.concat("/").concat(API.atoken).concat("/upload/").concat(picture).concat("/").concat(accuracy).concat("/").concat(latitude).concat("/").concat(longitude).concat("/").concat(timestamp).concat("/").concat(API.uid), true);
        xhr.onreadystatechange = function () {
            if (xhr.readyState == 4 && xhr.status == 200) {
                //Parse response to a JSON Object
                var data = JSON.parse(xhr.responseText);
                //If everything went right
                if (data.state) {
                    //Execute callback and pass ranking array
                    callback(null, {});
                }
                //Otherwise
                else {
                    callback({
                        //Methode for getting the reason of failure
                        'getReason': function (){
                            //Returns the reason sent from the server why the login request failed
                            return data.reason;
                        }
                    }, null);
                }
            }
        }
        xhr.send();
    }

Server side:

app.get('/:appid?/:atoken?/upload/:picture?/:accuracy?/:latitude?/:longitude?/:timestamp?/:userid?', function (req, res){
        console.log("Upload called");

        var picture = tools.escape(req.params.picture, "Picture", res);
        var accuracy = tools.escape(req.params.accuracy, "accuracy", res);
        var latitude = tools.escape(req.params.latitude, "latitude", res); 
        var longitude = tools.escape(req.params.longitude, "longitude", res);
        var timestamp = tools.escape(req.params.timestamp, "timestamp", res);
        var userid = tools.escape(req.params.userid, "Userid", res);
        var atoken = tools.escape(req.params.atoken, "Access token", res);
        var appid = tools.escape(req.params.appid, "Appid", res);

        db.atoken.findOne({"atoken": atoken}, function (err, data){
            if (err) { res.send(500, "error");  return;}
            //Note: db == Data Base
            //If there is a user with this acces token in the db
            if (data) {
                //Check if the id is the same
                //if (data._id == userid) {
                    //Save all the data in the db 
                    db.entries.save({"accuracy": accuracy, "latitude": latitude, "longitude": longitude, "timestamp": timestamp,"picture": picture, "userid": userid, "reviewed": false, "ip": req.ip, "date": new Date()});
                    res.send(200, {"state": true});
                //}
                //If the id is not the same return
                //else {
                //  res.send(400, {"state": false, "reason": "id is not the same"});
                //}
            }
            //If there is no such user in db --> return false
            else {
                res.send(400, {"state": false, "reason": "No such user in the system"});
            }
        });
    });