> ## Documentation Index
> Fetch the complete documentation index at: https://auth0.com/llms.txt
> Use this file to discover all available pages before exploring further.

> Describes how to migrate your applications based on the Guardian Android SDK to Firebase Cloud Messaging

# Migrate from Google to Firebase Cloud Messaging

As of April 11, 2019, [Google deprecated](https://firebase.googleblog.com/2018/04/time-to-upgrade-from-gcm-to-fcm.html) and replaced Google Cloud Messaging (GCM) with Firebase Cloud Messaging (FCM).

## Features affected

Auth0’s Guardian SDKs for iOS and Android help you to create custom mobile apps with Guardian functionality, providing secure access to <Tooltip tip="Multi-factor authentication (MFA): User authentication process that uses a factor in addition to username and password such as a code via SMS." cta="View Glossary" href="/docs/glossary?term=multi-factor+authentication">multi-factor authentication</Tooltip> (MFA) with push notifications.

Auth0's Guardian Android SDK library was built to send push notifications using GCM. Note that existing applications should [keep working as-is](https://aws.amazon.com/blogs/messaging-and-targeting/the-end-of-google-cloud-messaging-and-what-it-means-for-your-apps/).

## Actions

See [Google’s documentation](https://developers.google.com/cloud-messaging/android/android-migrate-fcm) to learn how to migrate from GCM to FCM.

The main difference between how you send notifications to GCM and FCM is in the payload received in the notification. While it was possible for existing customers using the Android SDK to adapt the payload received before calling the SDK method, we have upgraded the library so it accepts the new payload, making it simpler to adopt FCM. More details [here](https://github.com/auth0/Guardian.Android/pull/84).

The Guardian Android SDK 0.4.0 version is already available in Maven Central and includes this change. The sample application was also upgraded, so it can be tested by providing the `google-services.json` file and a `guardian-url`.