We run an agent built on Google's Agent Development Kit (ADK), deployed on Cloud Run with a Cloud SQL (PostgreSQL) session store via ADK's DatabaseSessionService. Bumping google-adk from 1.x to >=2.0.0 looked like a one-line dependency change. It wasn't.
Three things bit us, in increasing order of subtlety:
ADK 2.0 talks to Postgres through asyncpg, which forces a connection-URL change — and that URL is shared with sync code.
The events table needs two new columns that ADK 2.0 reads unconditionally. Deploy without them and chat silently 500s.
The legacy v0 (Pickle) schema still works, but throws a deprecation warning. Migrating to v1 (JSON) is optional and cannot be done in place.
