gem install error, index not found, ruby on rails

Question

Problem: Cannot install any gem, any type. But I want to install riddle if that matters.

When I run sudo gem install \"gem_name\" I get the following error:

Answer 1

You are running an old RubyGems version. Upgrade to the latest RubyGems 1.3.x branch.

$ rubygems update --self

If it doesn't work (RubyGems 1.2.0 has a weird bug that prevents --self update) then install rubygems_update

$ wget http://rubyforge.org/frs/download.php/60717/rubygems-update-1.3.5.gem
$ gem install rubygems-update-1.3.5.gem
$ update_rubygems

Use sudo if your os requires it.