FCM giving internal server error after updating APNs push certificate

Question

We are using firebase (fcm) to send notifications to iOS users. The app is live on app store and has active users. Push notifications were working but stopped suddenly when we changed our APNs certificate and uploaded the same in FCM. After this certificate all the push notifications have stopped to iOS devices and fcm is just returning a "internal server error" error message. We are in a very bad situation right now and would appreciate any help on this matter. Thanks in advance.

Derain

The problem seems to be with Firebase cloud messaging as the new certificate is working fine and delivering notifications when we connect to APNs directly – Derain