public async void Post() { var app = fireBaseAppProvider.Get(); var firebaseMessaging = FirebaseMessaging.GetMessaging(app); var to = mobileDevicesService.GetAll().ToList(); logger.LogInformation("Sending to {0} devices", to.Count); var message = new MulticastMessage { Notification = new Notification { Title = "Hello from api", Body = "Test message" }, Android = new AndroidConfig { TimeToLive = TimeSpan.FromMinutes(1) }, Tokens = to }; var result = await firebaseMessaging.SendMulticastAsync(message); logger.LogInformation("responce: {0}", JsonConvert.SerializeObject(result)); }