How do I use pg_dump and pg_restore to move a large database to another machine?
When you do

pg_restore --dbname=mydb --no-owner mydb.dump


You are trying to connect to the mydb database which still does not exist. Connect to an existent one and use the --create parameter:

pg_restore --dbname=existentdb --no-owner --create mydb.dump


http://www.postgresql.org/docs/current/static/app-pgrestore.html