Push Delivery Report explained

These responses we're getting from APNs (iOS, macOS) and FCM (Android, Chrome, Firefox) gateways when sending notifications there.

Most of the errors are not directly related with Pushwoosh rather the platform configuration or the gateway status.

General

Success

A notification has been successfully accepted by the gateway and should be sent to the corresponding device.

Unregistered

There is no such a token found on the gateway's side. Most likely because the application has been removed from the device or reinstalled. In case of removing, the token becomes invalid on the side of the gateway, however we can obtain such info only as a gateway response when sending a notification.

If the user installs the app again, we got a new token and will be able to send notifications again. See How is the Pushwoosh Hardware ID (HWID) generated? article for more info.

Such responses are just indicating of app removing/reinstalled, so this is not an error actually, rather that lifecycle of devices. For more information about device lifecycle, refer to this article: Device Lifecycle in Pushwoosh.

Note that neither APNs nor FCM reports an uninstalled token immediately — both do it on an undisclosed delayed schedule, so this status can appear days after the app was actually removed.

Frequency Capping

The message was blocked by the Global frequency capping limits set in your account.

• Cause: The user has already received the maximum allowed number of messages for the day/week.
• Action: You can adjust these limits in Settings > Message delivery settings > Frequency capping. For critical alerts, enable Send messages without global frequency capping in the message settings.

Processing Error

This category typically includes temporary internal failures or specific rejection reasons from the push gateway.

• Cause:
  • Temporary Failure: The APNs (iOS) or FCM (Android) server was temporarily unavailable.
  • Configuration Mismatch: Attempting to send to a token that doesn't match your current credentials or environment (e.g., mismatched Bundle ID).
• Action: If these errors are rare, they can be ignored as temporary glitches. If consistent, double-check that your iOS credentials and Bundle ID match your app exactly.

iOS

Invalid Token / Bad Device Token

This error usually points to the mismatch between gateways, i.e., you were sending pushes to your development/sandbox build through the production gateway or vice versa. It could be possible that some of your users have another build installed on their devices.

See more details here: Why am I getting an "Invalid Token" or "Bad Device Token" error for iOS push notifications?.

Connection failed

Generally, the "Connection failed" status points to some issues with your APNs credentials. Most likely, you are getting this error because the APNs certificate for this application has been revoked or has expired. A .p8 token key does not expire, which is why token-based configuration is the recommended setup.

Renew your credentials using our guide: iOS configuration.

Device Token Not For Topic

The Apple Push Notification service (APNs) identifies a mismatch between the push notification token and the app’s topic (typically the App ID). This mismatch prevents notifications from being delivered to devices.

See this article for the more info: [iOS] Got the DeviceTokenNotForTopic error.

In short, this happens when:

• The token issued to a device is linked to one Apple App ID, but the credentials configured on the server are for a different App ID.
• The APNs service attempts to send a push notification, but the topic (App ID) doesn't match the token on the device, triggering the error.

This error may occur during incorrect configuration of credentials on Pushwoosh side or the application bundle.

In some cases it may arise only for small amount of devices which are testing or developers ones. Such devices are usually subject to frequent changes of credentials or different test/stage build reinstalling. Typically, after the automatic token update on the affected devices (or reinstalling the build), such an error should disappear. We follow all Apple recommendations and best practices, updating tokens periodically.

However, if you see drastically increasing rates of this error, especially after a credentials update on the Pushwoosh application configuration or after releasing a new build in the store, please double-check your configuration and App ID.

Android, Chrome

Sender ID Mismatch

This is a response we receive directly from FCM (HTTP 403 SENDER_ID_MISMATCH): the authenticated sender is different from the sender the device's registration token was issued for. In practice it means the FCM service account key uploaded to Pushwoosh belongs to a different Firebase project than the one your app is built against.

Check that the google-services.json in your app and the service account JSON in Pushwoosh come from the same Firebase project, then re-upload the credentials using our guide: Android Firebase configuration. Affected devices get a valid token after the next app launch.

Invalid Registration

It means that the push token we tried to send the message to isn't valid. We remove such tokens from our database. Also, it's worth checking whether you have enabled notifications from your app on the device.

Not Registered

This status means one of the following:

• The device was unsubscribed from notifications;
• The application was deleted from the device;
• The push token of the device has expired. On Android, FCM expires a registration that has been inactive for 270 days.

Internal Server Error

It means that FCM itself failed to deliver the message to the device with the particular push token. These are transient — FCM asks senders to retry later, and Pushwoosh does.

Unauthorized

FCM rejected the request because it could not authenticate Pushwoosh as a sender for your Firebase project. This normally means the service account key stored in Pushwoosh was deleted or disabled in the Google Cloud console, or the Firebase Cloud Messaging API is turned off for the project. Re-generate the service account JSON and upload it again in the Android platform configuration.

Request Contains Invalid Parameters

An InvalidParameters / INVALID_ARGUMENT error is a direct response from the FCM gateway, and it indicates that a request with invalid parameters was rejected for the specified number of devices. Google does not document this response in detail.
It usually only occurs on just one or two devices, in most cases on testing devices. So it may be related to the code or build credentials.
Sometimes this response is related to using an outdated version of the Pushwoosh SDK, or to an incorrectly integrated SDK.

Firefox

Unknown Mozilla response code

This status means the token was issued by a very old Web SDK version whose token format Firefox no longer accepts. To fix it, update your site to the current Pushwoosh Web Push SDK (3.x) so that browsers are re-registered with valid tokens:

https://github.com/Pushwoosh/web-push-notifications