If you have just upgraded to the latest Ubuntu LTS 14.04 (Trusty Tahr), you might encountered a problem where Postgresql 9.3 is being installed along with your older version of Postgresql. It is recommended to upgrade your current setup to 9.3 and uninstall the older version.
Before you use pg_upgrade, make sure you shut down all Postgresql instances with
service postgresql stop
You can use the script below:
In the newer configuration file (postgresql.conf), switch the port to match the older version (from 5433 -> 5432).
Remove the older version using
sudo apt-get remove postgresql-9.1
and start the newer version using
sudo service postgresql restart
In the process of upgrading, I encountered
connection to database failed: fe_sendauth: no password supplied
I solved it by changing both pg_hba.conf (9.1 and 9.3) to use no password.
local all postgres trust
But, be sure to change back to previous setting before launching back your Postgresql.