This kind of error can not related to the database. It is a backend service error. Dropping the tables, if performed when the Server is down, causes no harm (beside deleting devices and subscriptions, of course).
We are in the process of developing a new version of the MPN Module that uses Firebase as a backend service. During this process we encountered this
MismatchSenderId error too, for our own demo project, after migrating it to Firebase. The only way to fix it was to use the previous sender ID on the app, the one we had before the migration (together with its previous API keys on the Server).
So far, our understanding of the Firebase migration process is that, once you migrate, the service console provides you with a new sender ID that is suitable for sending push notifications via Firebase Messaging only, not via GCM. I.e.:
- An app using a sender ID provided by the GCM console obtains device tokens that are suitable for use with GCM backend service only.
- An app using a sender ID provided by the Firebase console obtains device tokens that are suitable for use with Firebase Messaging backend service only.
In fact, we also encountered the opposite service error: Firebase Messaging refusing a push notification because the sender ID was still the one provided by the GCM console.
We will release the updated MPN Module soon, with it you will be able to use the new sender ID in your app. In the meantime, since the current MPN Module makes use of GCM, we are confident using your previous sender ID should fix the problem for you too.
