AngularJs $http.post() send data null state:-1

Could anyone tell me why the following statement does not send the post data to the designated URL?

login: function (username, password) {
    var deferred = $q.defer();

    var url = Config.serverUrl() + "/api-token-auth/";
    var data = {
        'username': username,
        'password': password
    };

    $http.post(url, data).then(function (responseData) {
        console.log(responseData);
        alert(url);
        alert(JSON.stringify(data));
        $localForage.setItem('shopper-user', responseData.data).then(function (user) {

            var token = "JWT " + user.token;
            $rootScope.token = token;
            $http.defaults.headers.common.Authorization = $rootScope.token;

            deferred.resolve(user);
        });

    }, function (error) {
        alert(url);
        alert(JSON.stringify(data));
        console.error(error);
        alert(JSON.stringify(error));
        deferred.reject(error);
    });

    return deferred.promise;
}

The URL is called on the server, but only go to the error state

Error:

{"data":null, "status":-1,"config":{"method":"POST"}}