Since I upgraded to Hardy Heron, I had to reinstall Ruby on Rails. I followed this howto. The code lines are:
# to make sure system is updated > sudo apt-get update > sudo apt-get dist-upgrade # get ready to build some software > sudo apt-get install build-essential # install all the stuff you need (like MySQL, ruby, rails, etc.) > sudo apt-get install ruby ri rdoc mysql-server libmysql-ruby ruby1.8-dev irb1.8 libdbd-mysql-perl libdbi-perl libmysql-ruby1.8 libmysqlclient15off libnet-daemon-perl libplrpc-perl libreadline-ruby1.8 libruby1.8 mysql-client-5.0 mysql-common mysql-server-5.0 rdoc1.8 ri1.8 ruby1.8 irb libopenssl-ruby libopenssl-ruby1.8 psmisc # get the ruby gems > wget http://rubyforge.org/frs/download.php/35283/rubygems-1.1.1.tgz > tar xvzf rubygems-1.1.1.tgz > cd rubygems-1.1.1 > sudo ruby setup.rb # make symbolic links > sudo ln -s /usr/bin/gem1.8 /usr/local/bin/gem > sudo ln -s /usr/bin/ruby1.8 /usr/local/bin/ruby > sudo ln -s /usr/bin/rdoc1.8 /usr/local/bin/rdoc > sudo ln -s /usr/bin/ri1.8 /usr/local/bin/ri # install rails > sudo gem install rails