On April 10, 2018, Google deprecated GCM. The GCM server and client APIs were removed on May 29, 2019, and currently any calls to those APIs can be expected to fail. Migrate GCM apps to Firebase Cloud Messaging (FCM), which inherits the reliable and scalable GCM infrastructure, plus many new features. See the migration guide to learn more.

Migrate to Firebase Cloud Messaging

Google Cloud Messaging, deprecated April 10 2018, has been deactivated and removed from Google's APIs. For equivalent functionality, use Firebase Cloud Messaging (FCM), which inherits the reliable and scalable GCM infrastructure, plus many new features. If you are an existing GCM user who has not yet migrated your system, see the migration guide for your platform.