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To send push notifications to users who download your Android app from the Google Play Store, you must create and upload a Firebase Cloud Messaging (FCM) Service Account private key to OneSignal.
These instructions do not apply to:
  • Web Push. Android devices can subscribe to your website or PWA without an FCM Service Account. See Web push setup.
  • Huawei apps distributed via the Huawei App Gallery. See Huawei Authorization.

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Requirements

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Create a Firebase Service Account private key

1

Create or open your Firebase Project

Go to your Firebase console and either create or select a project.
Firebase console showing the list of available projects
2

Enable Firebase Cloud Messaging API V1

In Project settings, select the Cloud Messaging tab.
Firebase Project settings showing the Cloud Messaging tab with the Firebase Cloud Messaging API (V1) status as Enabled
Check the Firebase Cloud Messaging API (V1) status:
  • If it shows Enabled (green checkmark), continue to the next step.
  • If it shows Disabled, click the 3-dot menu > Manage API in Google Cloud Console. In the Google Cloud Console, click Enable and wait for the green checkmark to appear with “API Enabled”.
Google Cloud Console Firebase Cloud Messaging API page showing the API Enabled status with a green checkmark
This is a good time to check if your Firebase Service Account has the required permissions:
  • cloudmessaging.messages.create
  • firebase.projects.get
Newly created Firebase projects usually have these permissions on the default Service Account. Check before continuing if you are unsure or working with an older project. See How do I check my Service Account permissions? for details.
3

Generate a new private key

Back in Project settings, select the Service accounts tab and click Generate new private key.
Service accounts tab in Firebase Project settings showing the Generate new private key button
Confirm by clicking Generate key in the popup.
Firebase confirmation dialog for generating a new private key for the service account
The downloaded private key contains sensitive credentials. Do not share it or check it into version control.
Save the .json file in a secure location. You will need it in the next section.

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Upload the Service Account private key to OneSignal

In your OneSignal dashboard:
1

Open Android settings

Go to Settings > Push & In-App > Platforms > Google Android (FCM).Click Activate (first-time setup) or Settings (if Android is already configured).
OneSignal Push & In-App Settings showing the Platforms tab with the Google Android (FCM) tile and a Settings button
2

Upload your Service Account private key

Click Select file and choose the .json private key you saved in the previous section.
OneSignal Google Android (FCM) configuration screen with the Service Account JSON file upload field and Select file button
3

Save and continue

Click Save & Continue. OneSignal validates the private key and moves you to the next step in the setup flow, where you select your SDK.
If the dashboard shows Invalid request or other errors, your Service Account is likely missing one or more required roles. See How do I check my Service Account permissions?.
Your OneSignal app is now connected to Firebase Cloud Messaging (V1). Next, follow Mobile SDK setup for the SDK you are using to install and initialize OneSignal in your app.

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FAQ

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How do I check my Service Account permissions?

Service Account permissions are managed in the Google Cloud Console, not the Firebase Console. The Service Account whose private key you upload to OneSignal must have both:
  • cloudmessaging.messages.create — granted by Firebase Cloud Messaging API Admin (roles/firebasecloudmessaging.admin).
  • firebase.projects.get — granted by Firebase Viewer (roles/firebase.viewer).
Broader roles like Firebase Admin (roles/firebase.admin), Editor, or Owner include both permissions and also satisfy the requirement. For OneSignal-only Service Accounts, prefer the narrow pair above to limit the impact if the private key is ever exposed. If the OneSignal dashboard shows Invalid request after you upload your Service Account private key, missing roles are the most common cause.
1

Open IAM in the Google Cloud Console

Sign in to the Google Cloud Console, select the project tied to your Firebase app, and go to IAM & Admin > IAM.
2

Find your Service Account

Match the principal email to the client_email field in your uploaded private key.
3

Add any missing roles

Click the pencil (edit) icon, then click Add another role to add either role if it is not already assigned.
4

Save

Click Save. IAM changes may take a minute to apply.

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Why am I seeing “This configuration is for a different Firebase Project”?

This error occurs when the uploaded private key belongs to a different Firebase project (a different Sender ID). Solution: Use the original Firebase project’s private key. If unavailable, contact support@onesignal.com with your App ID. Switching projects resets push tokens. Your users must reopen the app to get push again.

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Can I change my Sender ID?

Yes, but it will impact your existing users. Device tokens are tied to the original Sender ID. Changing it will invalidate existing tokens.
Users will stop receiving push notifications until they reopen the app and generate new tokens.
If you need help, contact support@onesignal.com with your App ID.

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Why don’t I see a Sender ID in OneSignal?

If your Firebase server key looks like AIz..., you’re likely using an outdated Google Cloud Messaging (GCM) setup. Create a new Firebase project and upload a Service Account private key.

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Do I need to update my code when switching to FCM V1?

No app or SDK changes are required. This is a dashboard-only update.

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What is the deadline for switching to FCM V1?

Google legacy FCM APIs are now fully deprecated. If you are still using the legacy APIs, you should migrate to FCM V1 immediately.

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How can I check which apps are still using the Legacy API?

Call the View an app API for each app and check the fcm_v1_service_account_json field in the response:
  • Present and non-empty: the app is on FCM V1.
  • Missing or empty: the app is not configured for FCM V1. If the app sends Android push, it is still on the Legacy API and must be migrated.
To list your apps and their App IDs first, use the View apps API.

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What is Firebase Cloud Messaging, and why does OneSignal need a Service Account private key?

Firebase Cloud Messaging (FCM) is Google’s service for delivering push notifications to Android devices. A Service Account is a Google identity that OneSignal uses to authenticate to your Firebase project, and its private key is a JSON file that proves the identity. Uploading the private key authorizes OneSignal to send pushes through Firebase on your behalf. For more details, see Google’s Service Account documentation.

Mobile SDK setup

Install and initialize the OneSignal SDK in your Android app.

Mobile push setup

Platform-specific setup steps for Android, iOS, and other mobile platforms.

Huawei push setup

Authorize OneSignal to send push to Huawei apps distributed via Huawei App Gallery.

Web push setup

Configure push notifications for websites.