If you configure in your pg_hba.conf file a connection by the md5 method and you didn't setup a password for that user, you must define a password by the "alter role" PostgreSQL command:
alter role user_name encrypted password 'user_password';
Also, if you is connecting by type TCP/IP (host) and your IP address is another than (localhost), as example (127.0.1.1) you must uncomment the following line at postgresql.conf file, adding your IP address:
listen_addresses = 'localhost,127.0.1.1'
After save the new configuration, you must restart your PostgreSQL service.
