Jekyll fails to serve (Ruby incompatible library version)
<p>When trying to run <code>jekyll serve</code>, it seems to build correctly (though with warnings that I haven't been able to resolve), but then fails to serve. <code>jekyll build</code> completes, but the resulting files are missing the compiled CSS.</p>

<p>Output from <code>jekyll serve</code>:</p>

<pre><code>Ignoring ffi-1.9.10 because its extensions are not built.  Try: gem pristine ffi --version 1.9.10
Ignoring curb-0.9.3 because its extensions are not built.  Try: gem pristine curb --version 0.9.3
Ignoring executable-hooks-1.3.2 because its extensions are not built.  Try: gem pristine executable-hooks --version 1.3.2
Ignoring ffi-1.9.10 because its extensions are not built.  Try: gem pristine ffi --version 1.9.10
Ignoring gem-wrappers-1.2.7 because its extensions are not built.  Try: gem pristine gem-wrappers --version 1.2.7
Ignoring json-1.8.2 because its extensions are not built.  Try: gem pristine json --version 1.8.2
Ignoring thin-1.6.1 because its extensions are not built.  Try: gem pristine thin --version 1.6.1
Configuration file: /home/jtebert/OwnCloud/Projects/Programming/python/AMS/mockup/_config.yml
            Source: /home/jtebert/OwnCloud/Projects/Programming/python/AMS/mockup
       Destination: /home/jtebert/OwnCloud/Projects/Programming/python/AMS/mockup/_site
 Incremental build: disabled. Enable with --incremental
      Generating... 
                    done in 1.404 seconds.
/usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:120:in `require': incompatible library version - /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/ffi-1.9.10/lib/ffi_c.so (LoadError)
        from /usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:120:in `require'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/ffi-1.9.10/lib/ffi.rb:6:in `rescue in &lt;top (required)&gt;'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/ffi-1.9.10/lib/ffi.rb:3:in `&lt;top (required)&gt;'
        from /usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:120:in `require'
        from /usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:120:in `require'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/rb-inotify-0.9.7/lib/rb-inotify/native.rb:1:in `&lt;top (required)&gt;'
        from /usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:68:in `require'
        from /usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:68:in `require'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/rb-inotify-0.9.7/lib/rb-inotify.rb:1:in `&lt;top (required)&gt;'
        from /usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:68:in `require'
        from /usr/lib/ruby/2.3.0/rubygems/core_ext/kernel_require.rb:68:in `require'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/listen-3.0.6/lib/listen/adapter/linux.rb:30:in `_configure'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/listen-3.0.6/lib/listen/adapter/base.rb:45:in `block in configure'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/listen-3.0.6/lib/listen/adapter/base.rb:40:in `each'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/listen-3.0.6/lib/listen/adapter/base.rb:40:in `configure'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/listen-3.0.6/lib/listen/adapter/base.rb:63:in `start'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/listen-3.0.6/lib/listen/backend.rb:26:in `start'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/listen-3.0.6/lib/listen/listener.rb:67:in `block in &lt;class:Listener&gt;'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/listen-3.0.6/lib/listen/fsm.rb:120:in `instance_eval'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/listen-3.0.6/lib/listen/fsm.rb:120:in `call'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/listen-3.0.6/lib/listen/fsm.rb:91:in `transition_with_callbacks!'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/listen-3.0.6/lib/listen/fsm.rb:57:in `transition'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/listen-3.0.6/lib/listen/listener.rb:90:in `start'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/jekyll-watch-1.3.1/lib/jekyll/watcher.rb:12:in `watch'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/jekyll-3.1.3/lib/jekyll/commands/build.rb:72:in `watch'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/jekyll-3.1.3/lib/jekyll/commands/build.rb:39:in `process'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/jekyll-3.1.3/lib/jekyll/commands/serve.rb:34:in `block (2 levels) in init_with_program'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/mercenary-0.3.5/lib/mercenary/command.rb:220:in `block in execute'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/mercenary-0.3.5/lib/mercenary/command.rb:220:in `each'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/mercenary-0.3.5/lib/mercenary/command.rb:220:in `execute'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/mercenary-0.3.5/lib/mercenary/program.rb:42:in `go'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/mercenary-0.3.5/lib/mercenary.rb:19:in `program'
        from /home/jtebert/.rvm/gems/ruby-2.0.0-p643/gems/jekyll-3.1.3/bin/jekyll:13:in `&lt;top (required)&gt;'
        from /usr/local/bin/jekyll:23:in `load'
        from /usr/local/bin/jekyll:23:in `&lt;main&gt;'
</code></pre>

<p>When trying to start a Jekyll project, I did have to create a link of Ruby versions because it was looking for 'Ruby2.1', but I'm not sure if this is playing a role in the current problem: <code>ln -s /usr/bin/ruby '/usr/bin/ruby2.1'</code>.</p>

<p>According to my package manager, I've installed Ruby 2.3.0. But according to <code>which ruby</code>, I'm using 2.0.0 which it's getting from rvm: <code>/home/xxxxxxx/.rvm/rubies/ruby-2.0.0-p643/bin/ruby</code>. And as I mentioned before, Jekyll seems to want v2.1 for something. I'm guessing these conflicting versions are somehow causing the problem, but I don't know how to resolve it.</p>