Postgres problem when unexpected shutdown.txt

If your computer was shut down in an unexpected way, an error could occur when launching your server

problem while using OauthProvider model:
 'could not connect to server: Connection refused
	Is the server running on host "localhost" (::1) and accepting
	TCP/IP connections on port 5432?
could not connect to server: Connection refused
	Is the server running on host "localhost" (127.0.0.1) and accepting
	TCP/IP connections on port 5432?
  
  Solution from http://stackoverflow.com/questions/19828385/pgconnectionbad-could-not-connect-to-server-connection-refused
  
  	
It could be as simple as a stale PID file. It could be failing silently because your computer didn't complete the shutdown process completely which means postgres didn't delete the PID (process id) file. The PID file is used by postgres to make sure only one instance of the server is running at a time. So when it goes to start again, it fails because there is already a PID file which tells postgres that another instance of the server was started (even though it isn't running, it just didn't get to shutdown and delete the PID).

1. Find the postgres data directory. On a MAC using homebrew it is /usr/local/var/postgres/, other systems it might be /usr/var/postgres/.
2. To make sure this is the problem, look at the log file (server.log). On the last lines you will see: FATAL:  lock file "postmaster.pid" already exists
HINT:  Is another postmaster (PID 347) running in data directory "/usr/local/var/postgres"?
3. If so, rm postmaster.pid
4. Restart your server. Should be working now.

Conclusion: Always be careful when shutting down your computer, and never run out of battery with a Rails server running :D