What does an 'Unregistered' push token error mean, and why does it happen?

An "Unregistered" error indicates that the push token associated with a device is no longer valid or recognized by the push notification service provider (e.g., Apple's APNS, Google's FCM). This means that notifications cannot be delivered to that specific device using that token.

Common reasons why a push token might become invalid or "Unregistered":

• For Mobile Apps:
  • The user uninstalled the application from their device.
  • The user disabled push notifications for your app in their device's system settings.
• For Web Browsers:
  • The user revoked push notification permissions for your website in their browser settings.
  • The browser's push subscription expired or was otherwise invalidated by the browser or its services.

What happens when a token is invalid? If a push token is invalid or "Unregistered," the user associated with that token will not receive any push notifications sent to it. To start receiving notifications again, the user would need to: * Reinstall the app (for mobile) and re-enable notifications if prompted or required by the app. * Re-enable push notification permissions for your website in their browser settings. This action will typically generate a new, valid push token for their device/browser.

Why does the system sometimes try to send to invalid tokens? Push notification platforms usually check the validity of a token at the time a message is sent. If a notification hasn't been sent to a particular token for some time, the system might not be aware that the token has become invalid in the interim. The system updates its information about a token's existence when it attempts to send a push notification. Sending regular notifications can help keep your list of active tokens more up-to-date.