Why did the number of 'Sent' pushes suddenly decrease significantly in my recurring Journey/Campaign?

A sudden drop in the 'Sent' count for a recurring campaign, especially when it affects only one platform, almost always points at the platform's push credentials.

Common causes (iOS)

• Expired .p12 certificate. APNs certificates expire roughly yearly. Once expired, APNs rejects every send and the 'Sent' count for iOS collapses.
• Certificate replaced incorrectly. If the new certificate's App ID/topic doesn't match the app, you get Device Token Not For Topic errors — the existing device tokens are not valid for the newly configured certificate, so nothing goes out.
• Wrong environment. A Sandbox certificate cannot deliver to Production tokens (and vice versa).

What to check

1. Open Settings > Configure platforms and review the iOS configuration: credential validity/expiry, Bundle ID match, and Sandbox vs Production.
2. Open the message's Errors breakdown in Message statistics to see the exact gateway error per platform.

Recommended fix: switch to token-based (.p8) authentication. A .p8 APNs authentication key does not expire, one key covers multiple apps and both Sandbox and Production, and it is the method recommended by both Apple and Pushwoosh. .p12 certificates are now considered the legacy option and should only be kept for existing setups. Note that iOS Live Activities require token-based configuration.

Android: the equivalent cause is a broken or replaced FCM v1 service-account JSON — legacy FCM Server Keys / Sender IDs were discontinued by Google in June 2024. Re-upload a valid service-account JSON for the correct Firebase project if Android sends dropped.