3.0 downgrade to 2.8

I have to downgrade my instances in order to connect some RAK Gateways that uses 2.x JSON encoding instead of the new protobuff.
Is it possible? How will DB migrations behave?
Thanks in advance.

It is possible, but it requires some manual steps. For each LoRa Server component you’ll find a migrations/ folder containing .sql files. You need find out which migrations to roll back and then apply the -- +migrate Down part of these files. Also make sure to remove these from the migration table in the database (this is currently named gorp_migrations).