So this tripped me up today and initial googling was not very helpful, maybe because I did not zero in on the right part of the error soon enough, but I hope you find this helpful.

I created a new Rails app and set up a Postgres database on my development machine. Then as soon as I tried to run rake db:create, I got the following error

could not connect to server: Connection refused
    Is the server running on host "localhost" ( and accepting
    TCP/IP connections on port 5432?

I ended up going down a different route, trying to figure out if the server is running, googling and renaming a pid file, etc…..

When I finally zeroed in on the port number at the end, I learned that I can check what port Postgres is listening on with sudo -u postgres psql -c "SHOW port;"

This showed me that postgres was running on 5433 while Rails was trying to connect to 5432. All I had to do was add a line in my database.yml to specify the port.

default: &default
  adapter: postgresql
  encoding: unicode
  host: localhost
  port: 5433
  username: postgres
  password: postgres
  pool: 5

Full disclosure, my username and password is something else, but if you are setting up Postgres in development for the first time, you can get away with these.

Problem solved!