Why am I seeing `SSL error: tlsv1 alert protocol version (PG::Error)` when connecting to my Heroku Postgres database?

Issue

I'm suddenly seeing database connection errors such as could not retrieve server_version: tlsv1 alert protocol version or SSL error: tlsv1 alert protocol version (PG::Error).

Resolution

Users of Heroku Postgres may start seeing errors when connecting to the database if their client is using a deprecated TLS version. Heroku Postgres databases do not accept connections using TLS v1.1 or lower.

Connections to Heroku Postgres databases require using TLS v1.2 or v1.3.