cordova ios error: ENOENT, open '/var/mobile/Containers/Data/Application/../../image.jpg in heroku

I am trying to make image upload from iphone. I am using ionic with cordova plugins in fontend and express/node.js in backend. This code works fine when i try in localhost. but when i run in heroku i am getting this error

error: ENOENT, open /var/mobile/Containers/Data/Application/../../image.jpg

I am using multer to handle multipart/form-data

on expressjs/node.js side i have

router.post('/me/avatar', ensureAuthenticated, function(req, res) {
fs.readFile(String(req.body.imageUrl).substring(7), function(err, data) {
    //using String(req.body.imageUrl).substring(7) to avoid file path like "file:///var/mobile/.." in ios simulator and iphone
    if (err) {
        console.log(err)
        res.send({
            message: "Error"
        })
    };

});

})

on ionic side i have

    $scope.updateAvatar = function() {
        var options = {
            maximumImagesCount: 1
        };
        $cordovaImagePicker.getPictures(options)
            .then(function(results) {
                $http.post(API_URL+"/users/me/avatar", {
                        imageUrl: results[0]
                    })
                    .success(function(response) {
                        var random = (new Date()).toString();
                        $scope.avatar = response.fullPath + "?cb=" + random;
                    })

            }, function(error) {
                // error getting photos
            });

    },