how to solve “ruby installation is missing psych” error?

Question

I used rvm to install ruby 1.9.3. even though it was successfully installed, it complained about libyaml. and now every time i wanna install a gem (say rails) this warning s

Answer 1

I tried all of these answers and still wasn't able to get it working. I installed libyaml with homebrew and then installed Ruby 1.9.3 and 2.0.0 with rvm. Each time it complained that I was missing psych (libyaml). But trying to install libyaml told me it was already installed. Rinse, repeat. Urgh.

Finally, what I did was to uninstall libyaml. Then I enabled autolibs in rvm, which (at least in OSX) allows rvm to install and manage dependencies more directly. Now when I installed the Rubies, rvm was able to install libyaml and recognize that it was in the right spot.

So if you've tried all of the other options, try actually removing libyaml and then installing your Rubies. It's count-intuitive from the error messages, but that's what finally worked for me.