Steps to upgrade a database from PostgreSQL 9.4 to PostgreSQL 9.5 using Homebrew (Mac OS X)
Notes:
- I don't use launchd to run Postgres.
- I don't have Homebrew installed in /usr/local, so I'm using commands that should work regardless of where it is installed.
This assumes you have already upgraded to 9.5 and got the fatal error trying to use your 9.4 database.
We need to have both 9.4 and 9.5 installed, so reinstall the old version.