I had a tid bit of trouble in updating the Ruby on Rails install that comes with leopard to the latest version. I kept getting error messages like:

wls08188:~ mbjerke$ gem update rails
Updating installed gems...
Attempting remote update of rails
Select which gem to install for your platform (universal-darwin9.0)
1. rails 2.0.2 ()
2. rails 2.0.1 (ruby)
3. rails 2.0.0 (ruby)
4. rails 1.2.6 (ruby)
5. Skip this gem
6. Cancel installation
> 1
Install required dependency activesupport? [Yn] Y
Select which gem to install for your platform (universal-darwin9.0)
1. activesupport 2.0.2 ()
2. Skip this gem
3. Cancel installation
> 1
ERROR: While executing gem … (OpenURI::HTTPError)
404 Not Found


Turns out the solution isn’t too painful:

sudo gem update --system

This will update the ruby gems package (to 0.9.5 at the time of this writing).

Then “gem install rails” works as expected.

Hope this helps someone

edit: Found this link after I figured it out on my own: http://weblog.rubyonrails.org/2007/12/19/trouble-installing-new-gems