engineer-push

iOS push notification delivery failures after an app update often stem from invalid APNs credentials, expired device tokens, or payload size limit violations. You must validate your .p8 or .p12 credential configuration, verify token registration state, and check payload format constraints to resolve the issue.

To set up web push notifications, you must configure VAPID keys and register a service worker to manage the subscription state. This process involves generating platform-specific credentials, constructing valid payloads, and handling browser subscription endpoints to ensure reliable delivery.

Token lifecycle management requires handling SDK registration flows, monitoring foreground versus background token states, and executing token reassignment when subscriptions change. Validating the subscription state and platform credentials ensures tokens remain active for campaign and API sends.

Interpreting APNs and FCM delivery error codes involves mapping status responses to specific credential misconfigurations, invalid token registration states, or payload format limits. Running delivery diagnostics and analyzing reporting metrics helps pinpoint whether the failure is due to authentication or message construction.

Cross-platform push notification composition requires adhering to strict payload size and format limits specific to APNs, FCM, and web push protocols. Validating notification channel configurations, TTL settings, and collapse keys ensures messages meet platform constraints before delivery.

Running push notification delivery diagnostics involves executing test-send workflows, checking platform credential validation, verifying token registration states, and reviewing frequency capping configurations. This workflow identifies whether failures originate from subscription issues or message payload constraints.