I have a problem after migration postgres instance from 9 to 12, we were following this method https://cloud.google.com/sql/docs/postgres/upgrade-db.
Before migration, I had a graph whit active connections on instance page and after the migration (on the new instance - postgres 12) - I don`t have values on this graph.
I am receiving a message like "No data is available for the selected time frame."
Also if I am run a query like "SELECT * FROM pg_stat_activity;" I see the number of connections.