When using Firebase SDK with cloud function to send push notification, below are some of the errors I encountered and its description related to iOS.


This error means that the authentication with the APNS failed. This is most likely due to not uploading the APNS key in the Firebase Cloud Messaging Settings.


This error is thrown when there is an issue with the token. This can arise from an invalid or expired token. This could also arise when a token obtained from iOS simulator is used. It's better to test push notification using an iOS device. Later versions of Xcode supports push notification on simulator but needs additional configuration.