PG::ConnectionBad - could not connect to server: Connection refused

Question

Every time I run my rails 4.0 server, I get this output.

Started GET "/" for 127.0.0.1 at 2013-11-06 23:56:36 -0500  PG::ConnectionBad - 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? could not connect to server: Connection refused Is the server running on host "localhost" (fe80::1) and accepting TCP/IP connections on port 5432? :  activerecord (4.0.0) lib/active_record/connection_adapters/postgresql_adapter.rb:825:in `connect'  activerecord (4.0.0) lib/active_record/connection_adapters/postgresql_adapter.rb:542:in `initialize'  activerecord (4.0.0) lib/active_record/connection_adapters/postgresql_adapter.rb:41:in `postgresql_connection'  activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:440:in `new_connection'  activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:450:in `checkout_new_connection'  activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:421:in `acquire_connection'  activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:356:in `block in checkout'  /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/monitor.rb:211:in `mon_synchronize'  activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:355:in `checkout'  activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:265:in `block in connection'  /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/monitor.rb:211:in `mon_synchronize'  activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:264:in `connection'  activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:546:in `retrieve_connection'  activerecord (4.0.0) lib/active_record/connection_handling.rb:79:in `retrieve_connection'  activerecord (4.0.0) lib/active_record/connection_handling.rb:53:in `connection'  activerecord (4.0.0) lib/active_record/migration.rb:792:in `current_version'  activerecord (4.0.0) lib/active_record/migration.rb:800:in `needs_migration?'  activerecord (4.0.0) lib/active_record/migration.rb:379:in `check_pending!'  activerecord (4.0.0) lib/active_record/migration.rb:366:in `call'  actionpack (4.0.0) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'  activesupport (4.0.0) lib/active_support/callbacks.rb:373:in `_run__1613334440513032208__call__callbacks'  activesupport (4.0.0) lib/active_support/callbacks.rb:80:in `run_callbacks'  actionpack (4.0.0) lib/action_dispatch/middleware/callbacks.rb:27:in `call'  actionpack (4.0.0) lib/action_dispatch/middleware/reloader.rb:64:in `call'  actionpack (4.0.0) lib/action_dispatch/middleware/remote_ip.rb:76:in `call'  better_errors (0.9.0) lib/better_errors/middleware.rb:84:in `protected_app_call'  better_errors (0.9.0) lib/better_errors/middleware.rb:79:in `better_errors_call'  better_errors (0.9.0) lib/better_errors/middleware.rb:56:in `call'  actionpack (4.0.0) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'  actionpack (4.0.0) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'  railties (4.0.0) lib/rails/rack/logger.rb:38:in `call_app'  railties (4.0.0) lib/rails/rack/logger.rb:21:in `block in call'  activesupport (4.0.0) lib/active_support/tagged_logging.rb:67:in `block in tagged'  activesupport (4.0.0) lib/active_support/tagged_logging.rb:25:in `tagged'  activesupport (4.0.0) lib/active_support/tagged_logging.rb:67:in `tagged'  railties (4.0.0) lib/rails/rack/logger.rb:21:in `call'  quiet_assets (1.0.2) lib/quiet_assets.rb:18:in `call_with_quiet_assets'  actionpack (4.0.0) lib/action_dispatch/middleware/request_id.rb:21:in `call'  rack (1.5.2) lib/rack/methodoverride.rb:21:in `call'  rack (1.5.2) lib/rack/runtime.rb:17:in `call'  activesupport (4.0.0) lib/active_support/cache/strategy/local_cache.rb:83:in `call'  rack (1.5.2) lib/rack/lock.rb:17:in `call'  actionpack (4.0.0) lib/action_dispatch/middleware/static.rb:64:in `call'  railties (4.0.0) lib/rails/engine.rb:511:in `call'  railties (4.0.0) lib/rails/application.rb:97:in `call'  rack (1.5.2) lib/rack/content_length.rb:14:in `call'  thin (1.5.1) lib/thin/connection.rb:81:in `block in pre_process'  thin (1.5.1) lib/thin/connection.rb:79:in `pre_process'  thin (1.5.1) lib/thin/connection.rb:54:in `process'  thin (1.5.1) lib/thin/connection.rb:39:in `receive_data'  eventmachine (1.0.3) lib/eventmachine.rb:187:in `run'  thin (1.5.1) lib/thin/backends/base.rb:63:in `start'  thin (1.5.1) lib/thin/server.rb:159:in `start'  rack (1.5.2) lib/rack/handler/thin.rb:16:in `run'  rack (1.5.2) lib/rack/server.rb:264:in `start'  railties (4.0.0) lib/rails/commands/server.rb:84:in `start'  railties (4.0.0) lib/rails/commands.rb:78:in `block in <top (required)>'  railties (4.0.0) lib/rails/commands.rb:73:in `<top (required)>'  bin/rails:4:in `<main>' 

I'm running Mavericks OS X 10.9 so I don't know if that's the problem. I've tried everything I could but nothing seems to work. I've uninstalled and install both postgres and the pg gem multiple times now.

This is my database.yml file

development:   adapter: postgresql   encoding: unicode   database: metals-directory_development   pool: 5   username:    password:    template: template0   host: localhost   port: 5432  test: &test   adapter: postgresql   encoding: unicode   database: metals-directory_test   pool: 5   username:    password:    template: template0   host: localhost   port: 5432  staging:   adapter: postgresql   encoding: unicode   database: metals-directory_production   pool: 5   username:   password:   template: template0   host: localhost  production:   adapter: postgresql   encoding: unicode   database: metals-directory_production   pool: 5   username:   password:   template: template0   host: localhost  cucumber:   <<: *test 

Answer 1

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. To fix it remove/rename the PID file. Find the postgres data directory. On macOS using homebrew it is in /usr/local/var/postgres/, or /usr/local/var/log/ other systems it might be /usr/var/postgres/. On M1, it might be /opt/homebrew/var/postgresql.
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. On a mac using launchctl (with homebrew) the following commands will restart the server.

   brew services restart postgresql 

OR on older versions of Brew

    launchctl unload homebrew.mxcl.postgresql.plist       launchctl load -w homebrew.mxcl.postgresql.plist 

Answer 2

You would need to restart the Postgresql Server.

If you are using ubuntu you can restart Postgresql by following command

sudo service postgresql restart