I am using PostgreSQL 10 with metabase locally on my computer, and I have this problem. I have added a database, however it does not sync its schema, and the console simply says:
"Connections could not be acquired from the underlying database" and after that error syncing database timezone and whatever else.
Also, when I visit my permissions page, I see that the administrator does not have access to the databases I'm connecting, and I cannot change it!!
In my case when I moved all Metabase files to a different folder this happened. I was using relative path for my SQLite db. I fixed the issue by giving the full path for my SQLite db.
p.s. I’m using Postgres 10 for internal db of Metabase and it is ok.