It seems your ruby installation is missing psych (for YAML output). To eliminate this warning, please install libyaml and reinstall your ruby.

[toamitkumar]

Getting this issue on Suse 11 sp1.

[sstephenson]

What version of Ruby are you trying to install? More info please.

[toamitkumar]

I tried ruby 1.9.3, though installing 192 works... is the issue related to libyaml being installed inside /usr/local/ruby-1.9.3-p0 ?

[toamitkumar]

So installing yaml inside /usr/local solves the problem
Looks like installing it inside /usr/local/ruby-1.9.3-p0 is the problem.
ruby is not able to find yaml while installing

[toamitkumar]

is there a command line arg to pass install location ??

[bbck]

I ran into this issue on Gentoo. I got around it by adding a configuration flag manually. I'm not sure why I have this issue only on this one box or why it wouldn't at least pick up the libyaml installed globally for the system ruby.

CONFIGURATION_OPTS="--with-opt-dir=/home/chris/.rbenv/versions/1.9.3-p0" ruby-build 1.9.3-p0 ~/.rbenv/versions/1.9.3-p0

[toamitkumar]

could not figure out a solution, compiling from source for both yaml and ruby seems to resolve the issue.

wget http://pyyaml.org/download/libyaml/yaml-0.1.4.tar.gz
tar xzvf yaml-0.1.4.tar.gz
pushd yaml-0.1.4
./configure --prefix=/usr/local
make && make install
popd

wget http://ftp.ruby-lang.org/pub/ruby/1.9/ruby-1.9.3-p0.tar.gz
tar xzvf ruby-1.9.3-p0.tar.gz
pushd ruby-1.9.3-p0
./configure --prefix=/usr/local --enable-shared --disable-install-doc --with-opt-dir=/usr/local/lib
make && make install
popd

[toamitkumar]

https://github.com/toamitkumar/chef-solo-capistrano/blob/master/bootstraps/ruby_1_9_3_p0.sh

[juhakaja]

I had something similar; curl gave an SSL certificate error - installation of 1.9.3 worked, but with issues with yaml. One quick and dirty an insecure way to fix it was to add an option -k after curl fetch command in ~/.rvm/scripts/fetch.

See more in http://stackoverflow.com/questions/6414232/curl-certificate-error-when-using-rvm-to-install-ruby-1-9-2

[paulnicholson]

Also experiencing this issue on gentoo. The command @bbck mentioned worked for me with a minor correction. Note, use full paths in place of ~/.

CONFIGURE_OPTS="--with-opt-dir=~/.rbenv/versions/1.9.3-p0" ruby-build 1.9.3-p0 ~/.rbenv/versions/1.9.3-p0

[sstephenson]

Would someone care to add a note about this to the wiki?

[x2002g]

In my case, it's fixed by installing "libtool". Maybe you can find your clue in file "yaml/make.log" as install log mentions.

[meisert]

I had the same problem in that the yaml installed in ruby 1.9.3 directory was referenced first, so the yaml in /usr/local/ didn't get referenced. This caused the above error.
The solution was to completely remove ruby 1.9.3 directories from the various locations in /usr/local/lib/ruby and then re-install (build & install) ruby again from source code. that got rid of the yaml I had created the first time I installed yaml I believe.
then I was able to upgrade my rubygems

[chemoish]

Thank you meisert...

I have no idea what I was doing, but after massive googling ultimately it came down to reinstalling ruby clean once installing libyaml.

// bye bye to you files
rm -rf /usr/local/lib/ruby/*
// cd ruby dir
./configure
make
make install

bingo - on centos 6.3 VirtualMachine

[sunild]

In my case, libyaml was already installed (according to yum). Instead of compiling libyaml from source, I installed the package "libyaml-devel" and then recompiled ruby w/out any special options. Fixed.

[ghost]

Having this same problem with Ruby 2.1.0-dev on CentOS 5.x ...is there a workaround? Tried compiling libyaml and then reinstalling with rbenv install 2.1.0-dev but still getting error:

It seems your ruby installation is missing psych (for YAML output).
To eliminate this warning, please install libyaml and reinstall your ruby.
/home/???/.rbenv/versions/2.1.0-dev/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:45:in `require': libyaml-0.so.2: cannot open shared object file: No such file or directory - /home/???/.rbenv/versions/2.1.0-dev/lib/ruby/2.1.0/x86_64-linux/psych.so (LoadError)

[ryansch]

This continues to be an issue. I just hit my head on this on a fresh install of 1.9.3-p392 on amazon linux release 2013.03.

Edit: Turns out I was having some 32 bit vs 64 bit issues.

[benzimmer]

We just had the problem on a freshly installed SLES 11 SP3.
Our solution is to install 2.1.x as usual

rbenv install 2.1.1

And then set

LD_LIBRARY_PATH=/home/$USER/.rbenv/versions/2.1.1/lib:$LD_LIBRARY_PATH

in the environment.

[jehos]

in my case on Ubuntu Zesty Zapus 17.04

jehos@MacBuntu:/usr/lib/ruby/2.3.0/psych⟫ dpkg -S /usr/lib/ruby/2.3.0/psych
libruby2.3:amd64: /usr/lib/ruby/2.3.0/psych

Let's satisfy dependency

jehos@MacBuntu:/usr/lib/ruby/2.3.0/psych⟫ sudo apt-get build-dep libruby2.3
Reading package lists... Done
Picking 'ruby2.3' as source package instead of 'libruby2.3'
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following NEW packages will be installed:
  chrpath libfontconfig1-dev libfreetype6-dev libgdbm-dev libncurses5-dev libncursesw5-dev libpng-dev libssl1.0-dev libxext-dev libxft-dev
  libxrender-dev libxss-dev systemtap-sdt-dev tcl8.6-dev tk8.6-dev x11proto-render-dev x11proto-scrnsaver-dev x11proto-xext-dev
0 upgraded, 18 newly installed, 0 to remove and 0 not upgraded.
Need to get 8,422 kB of archives.
After this operation, 24.3 MB of additional disk space will be used.
Do you want to continue? [Y/n] y

... blahblah ...

and then,

jehos@MacBuntu:~⟫ rbenv install 2.3.4
Downloading ruby-2.3.4.tar.bz2...
-> https://cache.ruby-lang.org/pub/ruby/2.3/ruby-2.3.4.tar.bz2
Installing ruby-2.3.4...
Installed ruby-2.3.4 to /home/jehos/.rbenv/versions/2.3.4

[billti]

FWIW: I was still getting this. I had Gems redirected to under my home folder. Removing the export GEM_HOME=$HOME/gems and export PATH=$HOME/gems/bin:$PATH from my .bashrc and relaunching the terminal fixed the issue for me.