PostgreSQL error 'Could not connect to server: No such file or directory'

Question

Like some others I am getting this error when I run rake db:migrate in my project or even try most database tasks for my Ruby on Rails 3.2 applications.

Answer 1

One of the reason could be that

unix_socket_directories in postgresql.conf file is not listed with the directory it is looking for.

In the question example it is looking for directory /tmp this has to be provided in the postgresql.conf file

something like this:

unix_socket_directories = '/var/run/postgresql,/tmp'    # comma-separated list of directories

This solution worked for me.