iOS: APNS connection closed error for push notifications

APNS connection is closed. We cannot count the exact number of delivered pushes.

This usually happens when testing an ad-hoc/enterprise build of the iOS App to test if notifications are working. The most likely cause is that your notification was sent via the wrong gateway due to a misconfiguration.

Apple has two notification gateways: one for sending to dev builds (sandbox) and the other for sending to production builds. To test with a production build you will need to have a production push notification cert uploaded. Navigate to Settings > Apps & sites > click on the matching iOS app > Push Settings. From this page, your iOS cert can be uploaded/re-uploaded as appropriate.

For help on generating iOS certificates, see iOS push notifications.