Clean install OSX 10.9.1 returns “undefined method `path2class'” when trying to install gems

Question

I just installed a clean Mavericks installation with Homebrew and RVM. Both brew doctor and rvm requirements return \"all good\", however, when I run <

Answer 1

I had the very same error and looked into the psych gem

$ gem list --local | grep psych
psych (2.0.4, 2.0.0)

as version 2.0.4 was recently installed I removed it, keeping only version 2.0.0

$ gem uninstall psych -v '2.0.4'
Successfully uninstalled psych-2.0.4

After that, everything worked fine again!