Rails 3.1 on Ubuntu 11.04 via RVM - uninitialized constant Psych::Syck

Question

gem install rails --pre
ERROR:  While executing gem ... (NameError)
    uninitialized constant Psych::Syck

I can't seem to find any info on how to resolve this. Has anyone else had the same problem?

I am using a newly created gemset in RVM with Ruby 1.9.2

Answer 1

I had exactly same problem on mac via RVM. Specifying version is the rescue for me.

gem install rails --pre --version 3.1.0.rc1

update (2011-06-12) with rubygems 1.8.4, I can install rails 3.1.0.rc4 without specifying the version.

Answer 2

I had exactly the same problem, and the other solutions mentioned here didn't work for me.

However, this did:

gem update --system