I am trying to build a todo list with Ruby and Ruby on Rails. In my rails application I add the gems I need and then type 'bundle' in my terminal. Everything works until:
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
/Users/Misha/.rbenv/versions/2.1.2/bin/ruby extconf.rb
Building nokogiri using packaged libraries.
-----
libiconv is missing. please visit http://nokogiri.org/tutorials/installing_nokogiri.html for help with installing dependencies.
-----
I go to the link provided and for mac it instructs to do the following commands:
sudo port install libxml2 libxslt
sudo gem install nokogiri
but then i get the command not found. I tried following a similar problem and solution:
sudo vi /etc/paths
Add 2 following lines:
/opt/local/bin
/opt/local/sbin
but still have the same problem.
I suspect sudo port install libxml2 libxslt is failing because you don't have the MacPorts package manager installed. However, I would install Homebrew instead (which is my personal package manager preference):
ruby -e "$(curl -fsSL https://raw.github.com/Homebrew/homebrew/go/install)"
Then continue with the instructions provided in the error message, substituting brew for sudo port:
brew install libxml2 libxslt
if that works, try:
sudo gem install nokogiri
Additionally to the answer of #thohl that I totally agree. Nokogiri sometimes is difficult to install. For that reason I keep the following recipe:
cd $( brew --prefix )
git checkout 763d946 Library/Formula/libxml2.rb
brew unlink libxml2
brew install libxml2 libxslt
git checkout master Library/Formula/libxml2.rb
ARCHFLAGS=-Wno-error=unused-command-line-argument-hard-error-in-future gem install nokogiri --verbose -- --with-xslt-dir=$( brew --prefix )/Cellar/libxslt/1.1.28 --with-iconv dir=$( brew --prefix )/Cellar/libiconv/1.14 --with-xml2-include=$( brew --prefix )/Cellar/libxml2/2.8.0/include/libxml2 --with-xml2-lib=$( brew --prefix )/homebrew/Cellar/libxml2/2.8.0/lib --use-system-libraries
These incantations made the trick in my case
I have the error below when installing rails on osx maverick. OpenSSL has been installed already. Does anyone know how to fix this issue?
$ gem install rails
ERROR: While executing gem ... (Gem::Exception)
Unable to require openssl, install OpenSSL and rebuild ruby (preferred) or use non-HTTPS sources
You may need to update your OpenSSL CA Bundle, per these instructions from chruby about Ruby 2.1.2 which state:
Install 2.1.2
Note: MRI 2.1.2 requires OpenSSL >= 1.0.1.
wget http://cache.ruby-lang.org/pub/ruby/2.1/ruby-2.1.2.tar.bz2
tar -xjvf ruby-2.1.2.tar.bz2
cd ruby-2.1.2
./configure --prefix=/opt/rubies/ruby-2.1.2
make
sudo make install
Note: OS X users must update their OpenSSL CA cert bundle and properly set ./configure --with-opt-dir to compile against Homebrew's libraries:
wget http://cache.ruby-lang.org/pub/ruby/2.1/ruby-2.1.2.tar.bz2
tar -xjvf ruby-2.1.2.tar.bz2
cd ruby-2.1.2
./configure --prefix="$HOME/.rubies/ruby-2.1.2" --with-opt-dir="$(brew --prefix openssl):$(brew --prefix readline):$(brew --prefix libyaml):$(brew --prefix gdbm):$(brew --prefix libffi)"
make
sudo make install
For me, it was enough to just update my OpenSSL CA cert bundle via Homebrew and then reinstall Ruby using ruby-install
brew tap raggi/ale
brew install openssl-osx-ca
ruby-install ruby 2.1.2
After I performed the above steps, the issue stopped presenting itself.
For me... I had tried installing ruby 2.1.2 with ruby-install (since I use chruby for my ruby version manager). I had tried manually installing openssl with homebrew, etc. But I still couldn't get ruby-install to successfully build ruby 2.1.2. I've also had similar issues in the past with installing rubies and ruby-build worked then so I gave I gave it a shot here and it worked! As I understand it, ruby-build is the installer used by rbenv.
What I did was:
rm -rf ~/.rubies/ruby-2.1.2 (This is where my ruby installs are installed at.)
brew remove --force openssl
brew install ruby-build
restart console to be safe
ruby-build 2.1.2 ~/.rubies/ruby-2.1.2
And success! ruby-build seems to be much smarter than ruby-install at successfully installing weird dependencies. I'm done with ruby-install at this point -- it's given me too many problems! (brew remove --force ruby-install)
I've had a similar issue.
A fix to rvm was introduced just yesterday, and it was not yet merged with rvm master branch, so this is how you do it:
rvm get branch /bugfix/3923_set_osx_brew_openssl_compiler_config
rvm install 2.4.0
gem install rails
If that works for you, go to the issue and tell the developer how much you appreciate his effort:
Recently I was struggling with ruby installations due to the recent auto-update in openssl version from 1.0 to 1.1.
I found out that the ruby version < 2.4 does not work with openssl version > 1.0.
I was not even able to revert back the openssl to 1.0 version because other libs has dependencies on it.
No other solution except the one given below worked for me:
brew install rbenv/tap/openssl#1.0
rvm reinstall 1.9.3-p551 --with-openssl-dir='/usr/local/opt/openssl#1.0'
gem update --system
Now my ruby runs with openssl 1.0 whereas all other libraries are running on the default openssl version 1.1.
secure server is the reason of this issue. You can Install it by using this command:
gem install rails --source http://rubygems.org
by default its using https://rubygem.org as the source for the gem.
$ gem install rails ERROR: While executing gem ... (Gem::Exception) Unable to
require openssl, install OpenSSL and
rebuild ruby (preferred) or use non-HTTPS sources
so we can specify a source, http//:rubygems.org which is a non-HTTPS source.
I am using osx 10.8.2 installed ruby 2.0 and....
got this when trying to run "sudo gem install rails"
$ sudo gem install rails
ERROR: Loading command: install (LoadError)
cannot load such file -- openssl
ERROR: While executing gem ... (NoMethodError)
undefined method `invoke_with_build_args' for nil:NilClass
I had ruby 1.9.x and rails 3.2.x working alright before
You have to install OpenSSL first and recompile ruby again:
RVM:
rvm pkg install openssl
rvm reinstall ruby-2.0.0-p0 --with-gcc=gcc-4.7 --with-openssl-dir=$rvm_path/usr
If you're using RVM please follow:
$ brew install automake
$ rvm pkg install openssl
$ rvm requirements run
$ rvm reinstall all --force
$ gem install rails
It worked for me.
I had very bad time with this ERROR.
Finally i done with it. There is only Once solution either you are with RVM or without RVM.
Make sure you have installed OpenSSL first BEFORE installing ruby.
RVM
Uninstall rvm
rvm implode
or
rm -rf ~/.rvm
Don’t forget to remove the script calls in your .bashrc and/or .bash_profile (or whatever shell you’re using).
sudo apt-get install zlib1g zlib1g-dev build-essential openssl libssl-dev libmysqlclient18 libmysqlclient-dev libyaml-dev curl git-core python-software-properties libpq-dev nodejs
Then install RVM, post ruby.
OR
rvm pkg install openssl
rvm reinstall ruby-2.0.0-p0 --with-gcc=gcc-4.7 --with-openssl-dir=$rvm_path/usr
WITHOUT RVM
First you should find where Ruby is:
whereis ruby
will list all the places where it exists on your system, then you can remove all them explicitly. Or you can use something like this:
rm -rf /usr/local/lib/ruby
rm -rf /usr/lib/ruby
rm -f /usr/local/bin/ruby
rm -f /usr/bin/ruby
rm -f /usr/local/bin/irb
rm -f /usr/bin/irb
rm -f /usr/local/bin/gem
rm -f /usr/bin/gem
THEN
sudo apt-get install zlib1g zlib1g-dev build-essential openssl libssl-dev libmysqlclient18 libmysqlclient-dev libyaml-dev curl git-core python-software-properties libpq-dev nodejs
apt-get -y update
apt-get -y install build-essential zlib1g-dev libssl-dev libreadline6-dev libyaml-dev
cd /tmp
wget http://cache.ruby-lang.org/pub/ruby/2.0/ruby-2.0.0-p247.tar.gz
tar -xvzf ruby-2.0.0-p247.tar.gz
cd ruby-2.0.0-p247/
./configure --prefix=/usr/local
make
make install
I hope this help you.
I fix this error for ruby 2.1.2 as follow.
rvm pkg install openssl
rvm reinstall ruby-2.1.2 --with-openssl-dir=$rvm_path/usr
On OSX, with rbenv and homebrew, the following worked for me:
brew install openssl
CONFIGURE_OPTS=--with-openssl-dir=$(brew --prefix openssl) rbenv install whatever-ruby-version
This worked for me which is similar to some of the other answers already posted.
rvm pkg install openssl
rvm reinstall all --force
When installing ruby 2.0, it is possible that rubygems 2.0 installation did not complete ok, because of openssl.
Make sure you provide a valid path to the openssl config file; you could:
find . -type f -name "openssl.cnf"
path is usually $HOME/.rvm/usr or $HOME/.rvm/usr/ssl
Then
[sudo] rvm reinstall ruby-2.0.0-p0 --with-openssl-dir=[openssl.cnf path] --verify-downloads 1
Make sure rubygems installation complete successfully.
Might be a better way to fix that path without reinstalling, but this should do it.
Make sure to check out this page on the rvm site: https://rvm.io/packages/openssl/
Running
rvm requirements run
gave me:
Missing required packages: autoconf, automake, libtool, pkg-config, apple-gcc42, readline, libxml2, libxslt, libksba, openssl, sqlite
after brew install autoconf automake ...
I was able to rvm reinstall 2.0.0 without openssl errors
I had the same problem with the same OS version. I use rvm and followed the steps in this command:
$ rvm requirements
Following those instructions, I ran:
$ brew update
$ brew tap homebrew/dupes
$ brew install bash curl git
$ brew install autoconf automake apple-gcc42 libtool pkg-config openssl readline libyaml sqlite libxml2 libxslt libksba
I had the same problem earlier, tried all of the snippets about and none of them worked out. After looking around for a bit the following worked for me:
$ rvm remove 2.0.0 # get rid of unsuccessful installation
$ rvm get head --autolibs=3 # get the latest RVM and build required libs
$ rvm requirements # just in case, install all other required stuff
$ rvm install ruby-2.0.0
$ rvm --default use ruby-2.0.0
What does rvm get head --autolibs=3 do exactly? I'm guess it automatically downloads dependencies, but I was hoping for a clear answer.
I encountered the same openssl error on Fedora when trying to use gem install <package>. It seems you need to install additional packages with yum/dnf
sudo dnf install rubygems rubygem-bundler ruby-devel mariadb-devel
After running the above command, gem install <package> should now work.
just went through the same problem. Takes a bit time but, upgrading openssl with
brew upgrade openssl#1.1
worked for me. Version might be different in the future, type brew install openssl to see which version you can upgrade to. I hope it helps.
If you have libssl1.1, your problem may be that these older versions of ruby (2.4 is the cutoff) are only compatible with libssl1.0.
For debian/ubuntu, please ensure that apt-get install libssl1.0-dev succeeds.
If you are using ruby-install, it will take the same openssl argument as rvm:
ruby-install ruby-2.0.0-p247 -- --with-openssl-dir=/usr/local/opt/openssl
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 shows up:
It seems your ruby installation is missing psych (for YAML output). To eliminate this warning, please install libyaml and reinstall your ruby.
I use Mac os X 10.7 (Lion).
In my case
rvm pkg install libyaml
and
rvm reinstall ruby-1.9.3-p125
solved the problem.
For people using Ubuntu, make sure that libtool is installed prior to the steps above:
sudo apt-get install libtool
For macOS users (with homebrew):
rm -rf /usr/local/lib/ruby/gems/ && brew reinstall ruby
brew install libyaml
rvm reinstall 1.9.3
Is what worked for me (on Snow Leopard).
for ubuntu and rvm
sudo apt-get install libtool
rvm pkg install libyaml
rvm reinstall 1.9.3
worked
If not using rvm, but rather you are building and installing ruby 1.9.3 from scratch — for example, you're managing your ruby versions with rbenv — you must install libyaml first. Get it from http://pyyaml.org/; at the moment, the file you want is http://pyyaml.org/download/libyaml/yaml-0.1.4.tar.gz. Open the tarball and cd into the resulting folder. Then:
./configure --prefix=/usr/local
make
sudo make install
You are now ready to build ruby. Download ruby from http://ftp.ruby-lang.org/pub/ruby/. Open the tarball and cd into the resulting folder. Now:
./configure --prefix=/wherever/you/want/it/to/go
make
make install
(Or possibly sudo make install, depending on where you're putting it.) If using rbenv, you'll know it has worked if you switch to rbenv global 1.9.3-p194 (or whatever your version is called) and gem --version works without a warning. That worked for me on Mac OS X 10.6.8. (Update: I just tried this on Mac OS X 10.8.1 and it seems to have worked fine there too.)
In my case the solution was to add the psych gem to the Gemfile.
I had this problem. libyaml wouldn't compile. It turns out I was missing libtool.
yum install libtool
yum install libyaml (or rvm pkg install libyaml)
rvm reinstall 1.9.3
That solved my problem.
If you have installed ruby on macOS with homebrew, try this solution.
rm -rf /usr/local/lib/ruby/gems/ && brew reinstall ruby
Note that this will get rid of all installed gems. Best save a list of installed gems with gem list before you run this.
$ brew doctor
$ brew link libyaml
I reinstalled ruby 1.9.3 with libyaml support:
rvm reinstall 1.9.3 --with-libyaml
I made sure that I would use 1.9.3 before installing psych:
rvm use 1.9.3
I installed psych:
gem install psych
I got this fixed finally. The issue was that even though I installed libyaml with brew, it was never linked. I had to remove a conflicting header file and then brew link libyaml.
Installing ruby with rvm for mac osx, use autolibs to install libyaml and first uninstalling libyaml helps.
This worked for me:
brew uninstall libyaml
rvm autolibs enable
rvm reinstall ruby-2.1.1
I had the same problem (Lion 10.7.4), and fixed it by upgrading rvm then reinstalling ruby
1) upgrade rvm https://rvm.io//rvm/install/
curl -L https://get.rvm.io | bash -s stable --ruby
2) Then use rvm to reinstall ruby 1.9.3 (which had been previously installed with the earlier version of rvm)
rvm reinstall 1.9.3
sudo port install libyaml # or brew install libyaml
rvm get latest
rvm pkg install iconv
rvm pkg install openssl
rvm reinstall 1.9.3 --with-openssl-dir=~/.rvm/usr --with-iconv-dir=~/.rvm/usr
curl -OL http://rubyforge.org/frs/download.php/75414/linecache19-0.5.13.gem
curl -OL http://rubyforge.org/frs/download.php/75415/ruby-debug-base19-0.11.26.gem
gem install linecache19-0.5.13.gem ruby-debug-base19-0.11.26.gem -- --with-ruby-include=$rvm_path/src/ruby-1.9.3-p125/
gem install ruby-debug19
rvm reload
reload your .rvmrc (cd out, cd in)
bundle
None of these answers worked for me.
I found my answer on https://github.com/sstephenson/ruby-build/issues/119
I am on Centos 6.3 Virtual Machine.
YOU MUST install libyaml before you install ruby. IF you ALREADY installed ruby you must get rid of the files before compiling source again!!!
# cd to your ruby source location
rm -rf /usr/local/lib/ruby # clean out ruby files
./configure
make && make install
gem -v # check if error is fixed
I built the libyaml files separately from source and installed them in /usr/local/lib. The ruby that RVM created still did not see them, and rather than muck with the makefile or the system LD_LIBRARY_PATH I just copied /usr/local/lib/libyaml* to ~/.rvm/rubies/ruby-1.9.3-p327/lib/
That quieted the warning.
This is what worked for me on Ubuntu:
- installing libyaml-dev (sudo apt-get install libyaml-dev)
- installing rvm + ruby 1.9.3
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.
I had the same problem (Cent OS 5.7), none of the above solutions worked to me.
// My console warning
/usr/local/rvm/rubies/ruby-1.9.3-p286/lib/ruby/1.9.1/yaml.rb:56:in `<top (required)>':
It seems your ruby installation is missing psych (for YAML output).
To eliminate this warning, please install libyaml and reinstall your ruby.
After doing several re-installs, I realized it's looking for yaml in ruby version of 1.9.1 instead of 1.9.3. So i downgraded
// obviously after installing `libyaml`
rvm remove all
rvm install 1.9.1
rvm use 1.9.1 --default
And it worked 8D!
On CentOS 6.3 none of the above worked. However installing libyaml from source before installing ruby resolved the problem.
$ wget http://pyyaml.org/download/libyaml/yaml-0.1.4.tar.gz
$ tar xzvf yaml-0.1.4.tar.gz
$ cd yaml-0.1.4
$ ./configure --prefix=/usr/local
$ make
$ sudo make install
and then
rvm install 1.9.3
gem install rails
I'm using
rvm 1.16.20 (version) by Wayne E. Seguin ,
Michal Papis [https://rvm.io/]
and also got the following error during bundle install
.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/yaml.rb:56:in `': It seems
your ruby installation is missing psych (for YAML output). To
eliminate this warning, please install libyaml and reinstall your
ruby.
Here are three different ways to resolve this error w/o having to gem install psych
export LD_LIBRARY_PATH=/usr/local/lib
alter /etc/ld.so.conf
sudo su - root
echo /usr/local/lib64 >> /etc/ld.so.conf
echo /usr/local/lib >> /etc/ld.so.conf
ldconfig
Fix rvm ruby 1.9.3 installation via
patch .rvm/scripts/functions/manage/ruby < ruby-1.9.3-LDFLAGS.patch
rvm uninstall ruby-1.9.3-p194
export LDFLAGS='-L /usr/local/lib64 -L/usr/local/lib -Xlinker -R/usr/local/lib64 -Xlinker -R/usr/local/lib'
rvm install ruby-1.9.3-p194 --disable-binary
grep configure_args .rvm/src/ruby-1.9.3-p194/config.log # to confirm LDFLAG
$ diff -c .rvm/{src/rvm/,}scripts/functions/manage/ruby
*** .rvm/src/rvm/scripts/functions/manage/ruby 2012-11-10 06:28:14.000000000 +0000
--- .rvm/scripts/functions/manage/ruby 2013-01-25 17:18:00.000000000 +0000
***************
*** 106,123 ****
# when relative is in effect libyaml is installed in ruby itself so it will be moved with ruby
prefix_path="${rvm_rubies_path}/${rvm_ruby_string}" libyaml
! __rvm_update_configure_env CFLAGS="-I${rvm_rubies_path}/${rvm_ruby_string}/include"
! __rvm_update_configure_env LDFLAGS="-L${rvm_rubies_path}/${rvm_ruby_string}/lib"
if [[ -d "${rvm_rubies_path}/${rvm_ruby_string}/lib64" ]]
! then __rvm_update_configure_env LDFLAGS="-L${rvm_rubies_path}/${rvm_ruby_string}/lib64"
fi
else
libyaml_installed || libyaml # Installs libyaml
! __rvm_update_configure_env CFLAGS="-I${rvm_path}/usr/include"
! __rvm_update_configure_env LDFLAGS="-L${rvm_path}/usr/lib"
if [[ -d "${rvm_path}/usr/lib64" ]]
! then __rvm_update_configure_env LDFLAGS="-L${rvm_path}/usr/lib64"
fi
fi
--- 106,123 ----
# when relative is in effect libyaml is installed in ruby itself so it will be moved with ruby
prefix_path="${rvm_rubies_path}/${rvm_ruby_string}" libyaml
! __rvm_update_configure_env CFLAGS="-I${rvm_rubies_path}/${rvm_ruby_string}/include ${CFLAGS}"
! __rvm_update_configure_env LDFLAGS="-L${rvm_rubies_path}/${rvm_ruby_string}/lib ${LDFLAGS}"
if [[ -d "${rvm_rubies_path}/${rvm_ruby_string}/lib64" ]]
! then __rvm_update_configure_env LDFLAGS="-L${rvm_rubies_path}/${rvm_ruby_string}/lib64 ${LDFLAGS}"
fi
else
libyaml_installed || libyaml # Installs libyaml
! __rvm_update_configure_env CFLAGS="-I${rvm_path}/usr/include ${CFLAGS}"
! __rvm_update_configure_env LDFLAGS="-L${rvm_path}/usr/lib ${LDFLAGS}"
if [[ -d "${rvm_path}/usr/lib64" ]]
! then __rvm_update_configure_env LDFLAGS="-L${rvm_path}/usr/lib64 ${LDFLAGS}"
fi
fi
I also struggled with the same failures with rvm install ruby-2.0.0 for many, MANY hours. I had tried all the different methods to install libyaml; wget source, yum and rvm. I also tried all of the different approaches listed in similar threads. Because I tried all the different methods, I had multiple installations and locations of libyaml.
RVM is perfectly capable of installing the necessary dependencies in ~/.rvm. Simply removing the libyaml files from non-RVM install fixed this issue for me:
sudo rm /usr/local/lib/libyaml*.*
rvm reinstall ruby-2.0.0-p0
Works!
NON-RVM ruby install method.
% uname -a
Linux localhost.localdomain 2.6.32-358.el6.x86_64 #1 SMP Fri Feb 22 00:31:26 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
% cat /etc/redhat-release
CentOS release 6.4 (Final)
% wget http://apt.sw.be/redhat/el5/en/x86_64/dag/RPMS/rpmforge-release-0.3.6-1.el5.rf.x86_64.rpm
% sudo rpm -K rpmforge-release-0.3.6-1.el5.rf.*.rpm"
% sudo rpm -ivh rpmforge-release-0.3.6-1.el5.rf.*.rpm"
DISABLE rpmforge by editing this file and set enabled=0
% sudo vi /etc/yum.repos.d/rpmforge.repo
% grep rpmforge ~/.aliases
alias rpmforge "sudo yum --disablerepo='*' --enablerepo='rpmforge'"
% rpmforge install libyaml libyaml-devel
% sudo yum list installed | grep libyaml
libyaml.x86_64 0.1.4-1.el5.rf #rpmforge
libyaml-devel.x86_64 0.1.4-1.el5.rf #rpmforge
The libyaml-devel is the key.
% tar zxvf ruby-1.9.3-p448.tar.gz
% cd ruby-1.9.3-p448
% ./configure -prefix=$HOME/ruby-1.9.3-p448
% make ; make install
% cd $HOME; ln -s ./ruby-1.9.3-p448 ruby
Update your path and source .cshrc
% echo $PATH
/home/francis/ruby/bin:/usr/sbin:/home/francis/bin:/home/francis/jdk1.7.0_25/bin:/usr/lib64/qt-3.3/bin:/usr/local/bin:/usr/bin:/bin
% which ruby
/home/francis/ruby/bin/ruby
% gem update --system
Set your GEM_HOME in .cshrc and source
% echo $GEM_HOME
% /home/francis/ruby/lib/ruby/gems
% gem install mysql2 pg ruby-debug-ide rails capistrano capistrano-ext passenger
If you are building ruby from source (I built 1.9.3 on Fedora 20), you will need this before you do the configure/make to build ruby:
yum install libyaml-devel
(in addition to yum install libyaml.) Similar to Francis's answer using rpmforge above.
I was having this error and noticed I had different versions of Ruby installed with HomeBrew, along with many gems that I no longer used. So did a full clean up like this:
$ brew remove --force ruby # remove all versions installed
$ sudo rm -rf /usr/local/lib/ruby # remove all gems and leftover files
$ brew install ruby
$ gem install bundler
$ bundle install
If you don't use a Gemfile, make sure you know which gems to reinstall.
In my case all I needed to do was
rm -rf /usr/local/lib/ruby/gems/2.4.0/gems/psych-2.2.4
rm -rf /usr/local/lib/ruby/gems/2.4.0/extensions/x86_64-darwin-16/2.4.0/psych-2.2.4
Now, FWIW, gem list includes
psych (2.2.4, default: 2.2.2)
Ubuntu
Using RVM
Reason: Conflicting Psych gem versions between ruby 2.4.4 and ruby 2.5.1
I spent a few hours trying to get my error to go away and none of the replies here suited my case, so I thought I would post how I solved it...
In my case when I ran gem list | grep psych, I had the following output: psych(default: 3.1.0, default: 3.0.2).
Apparently since version 2.5.0, ruby depends on the newer version of psych (3.1.0) and having both set as default was messing up everything. Notice that I never ended up finding out why those were both set as default - I completely wiped out rvm and ruby versions from my computer due to this.
So in order to remove the older version (3.0.2) from being set as default, head to ~/.rvm/gems/ruby-x.x.x#global/specifications/default. If you run ls | grep psych it will return both versions of the gem here. If you want to maintain 3.1.0 as default just run mv psych-3.0.2.gemspec ../ and then try running gemlist to make sure it is listing only one version as default now...
tl;dr
cd /.rvm/gems/ruby-x.x.x#global/specifications/default
mv psych-3.0.2 ../
Hope this helps someone!
On Snow Leopard, the solution by Catharz did not work for me. This solution, however, did:
brew install libyaml
rvm get head
rvm reinstall 1.9.3 --with-gcc=clang
(The rvm reinstall gave me a warning about clang not having the option "--with-libyaml" but it solved the error message regardless.)
This worked for me at least on Ubuntu 10.04
$ sudo apt-get install libtool
$ rvm reinstall 1.9.3
On Solaris:
# sudo crle -64 -l /usr/local/lib
to add /usr/local/lib to the shared library search path
(see man crle)
When I switch from 64 bit to 32 bit on Snow Leopard 10.6.8, I had reinstalled ruby (used rvm) to run on 32bit and met the same problem. So I just 'cleanup' all thing that cached by rvm before and problems solved. Hope this tip can help someone.
rvm cleanup all
rvm install ruby_version_here //(This way, rvm will also re-download newest yaml).
BTW, if you still meet this problem, I think you can try:
gem install psych