Having same problem on OSX Yosemite:

/.rvm/gems/ruby-2.1.5/gems/safe_yaml-1.0.4/lib/safe_yaml/psych_resolver.rb:4:in `class:PsychResolver': uninitialized constant Psych::Nodes (NameError)

I noticed this in the safe_yaml readme:

When you require the safe_yaml gem in your project, YAML.load is patched to accept one additional (optional) options parameter.
This changes the method signature as follows:
for Syck and Psych prior to Ruby 1.9.3: YAML.load(yaml, options={})
for Psych in 1.9.3 and later: YAML.load(yaml, filename=nil, options={})

I'm going to explore Jekyll to see how it's using safe_yaml in the latest release.

I'm affected by this as well with Jekyll 2.5.3 & safe_yaml 1.0.4, but not with Jekyll 2.4.0 & safe_yaml 1.0.0. (MRI Ruby 2.2.0)

Strangely enough, this looks like it could be a problem with Psych itself? I attached pry in psych_resolver.rb, did a show-source on Psych, and it looks like it's being overridden or Psych::Nodes is not being exported after loading psych in psych_handler.rb.

https://gist.github.com/singularperturbation/ec150255a8be199f8e80

Having the same problem: Jekyll 2.5.3, safe_yaml 1.0.4, Ruby 2.2 and Psych 2.0.8

I'm finding I've got to back down to Psych 2.0.5 with Jekyll 2.5.3 and safe_yaml 1.0.4, in order to solve the issue.

I think psych comes with Ruby & is compiled with a specific Ruby in mind, so you would need to upgrade Ruby to upgrade Psych. C extensions/dylib's etc.

@egyptiankarim Your solution worked for me.

@egyptiankarim I've had Psych 2.0.5, Jekyll 2.5.3 and safe_yaml 1.0.4 installed all along, so I don't think this is the solution for me since I received the error with these versions installed.

Also, I'm running Ruby 2.1.0 which installs from running gem update --system on a Mac.

Now, I've updated all my gems and cleaned out old ones. Psych was updated to 2.0.10. There was no update to safe_yaml. Anyway, the error still persists.

@djmtype Try using Ruby 2.2.0 with the correct versions for Psych, Jekyll, and safe_yaml, and see if the problem persists.

The same problem, all recent version of psych Jekyll and safeyaml and error exists

Had the same problem. Fixed this by using Psych 2.0.5:

gem uninstall psych
gem install psych -v 2.0.5

Not sure if that was the most elegant solution.

@EvanHahn That didn't do it for me. What Ruby version do you have installed?

@djmtype 2.2.0.

@EvanHahn Thanks. Ok, I'm still on Ruby v2.1.0.

The culprit might be psych…

gem list reveals psych (2.0.5,2.0.2) So, I ran, sudo gem uninstall psych -v 2.0.2 but it returned an error:
ERROR: While executing gem ... (Gem::InstallError) gem "psych" cannot be uninstalled because it is a default gem

But, according to gem-list v2.0.2 follows after v2.0.5 in the list. Is v2.0.5 not the default version the system is using? [Confused.]

So, I uninstalled v2.0.5 because it won't allow me to uninstall v2.0.2.

Jekyll works! thus far

Hey,

gem cleanup

... fixed it for me

Regards,

Running gem cleanup never resolved the issue of removing psych 2.0.2 when I also had 2.0.10 installed. That's the problem. It still leaves 2.0.2 installed.

Running gem update psych will not update psych from 2.0.2 to 2.0.10. Instead, it will install v 2.0.10 in addition.
psych (2.0.10, 2.0.2)

This is why jekyll is failing with Ruby 2.1.0. Psych 2.0.10 doesn't seem compatible with this version of Ruby or another gem.

Running gem uninstall psych automatically removes the latest version, 2.0.10. The oddity in that is I'm usually prompt to which version I'd like to remove if there are multiple versions of the same gem installed.

To piggyback, gem list for me showed psych (2.0.5, 2.0.0).

I removed 2.0.5 (seems to be the problem) with sudo gem uninstall psych -v 2.0.5

I was then able to install Jekyll correctly with sudo jekyll new .

Hope that helps someone.

What are the correct gem versions of Psych, Jekyll and Safe_yaml to work with ruby 2.2.0? Ive tried various versions of all gems but still get the same error.

@dhcodes solved.

gem list

psych (2.0.12, 2.0.8)

I removed version 2.0.8 and worked!!

Uninstalling psych-2.0.12 and keeping only psych-2.0.5 solved the problem for me.

Removing all but one of the versions of psych seems like the wrong solution. Why does safe_yaml have this problem?

I've submitted #74 which adds require "psych/nodes" on the file that causes the issue. That hopefully should solve the problem.

I have a feeling that there's something going on with the load order, and that's why you're not seeing it with psych <= 2.0.5. I didn't spend time to debug it, because explicitly requiring stuff before use feels like the right fix to me anyway.

@ldexterldesign That solution: gem cleanup worked for me as well. Not sure why... I'm running ruby 2.2.0 on a windows box even.

@ldexterldesign @seanriceaz I also confirm the gem cleanup works. I'm on Mac Yosemite, rbenv with ruby 2.2.0

gem cleanup didn't work for me. I resolved this issue by removing all installed gems followed by gem install github-pages.

'bundle exec' worked for me...

-> jekyll serve # I get the error

-> bundle exec jekyll serve # no error :) happy days

you can put this in your .zshrc (or similar) to make it happen automatically:

# Bundle exec commands
bundle_commands=( rake spec rspec cucumber cap watchr rails rackup jekyll )
function run_bundler_cmd () {
    if [ -e ./Gemfile ]; then
        echo "bundle exec $@"
        bundle exec $@
    else
        echo "$@"
        $@
    fi
}
for cmd in $bundle_commands
do
    alias $cmd="run_bundler_cmd $cmd"
done

This:

gem uninstall psych
gem install psych -v 2.0.5

from @EvanHahn worked for me!

Doing gem update --system and then gem update solved the problem for me.

Thanks @EvanHahn! Your suggestion worked.

@ldexterldesign gem cleanup worked for me on Yosemite 10.10.3 with RVM with Ruby 2.1.2 (default).

I had this problem with Ruby 2.2.0 and Jekyll (2.0.12 2.0.8) installed. Uninstalling 2.0.12 worked for me. Is it possible that having a version of Psych other than the default version associated with the Ruby version is causing an error?

gem uninstall psych -v 2.0.12

Thanks to @djmtype

gem update --system works on me.

gem version updated frome 2.4.5 to 2.4.8.
ruby version 2.2.2; safe_yam-1.0.4

gem cleanup works for me.

jekyll (2.5.3)
jekyll-coffeescript (1.0.1)
jekyll-gist (1.2.1)
jekyll-paginate (1.1.0)
jekyll-sass-converter (1.3.0)
jekyll-watch (1.2.1)
safe_yaml (1.0.4)
psych (2.0.13, 2.0.8)

gem cleanup solved it for me as well.

gem cleanup did not work for me; however, gem uninstall psych removed one of the two installed packages and now it works.

gem cleanup worked for me. ✌️

psych -v 2.0.5 work for me, thanks for the solution

thanks! its work.
after i run 'gem update', that's trigger this mess for me.
i do 'gem cleanup'
and 'gem uninstall psych'

@sjackman your solution worked for me, thanks! 👍

The different mix of 'gem update,' 'gem cleanup,' and 'gem uninstall psych' didn't fix it.

OS 10.11.1 over here

gem update --system work for me

gem cleanup work for me

I had the same error after running gem update, running gem cleanup fixed the problem.

Running gem cleanup only works until your next gem update. It's a temporary fix.

I'm still suffering from this on Ruby 2.2.3 with:

• psych (2.0.17, 2.0.8)
• safe_yaml (1.0.4)
• jekyll (3.1.2, 3.0.1)

Forcing psych 2.0.8 is a workaround.

gem uninstall psych

ERROR: While executing gem ... (Gem::InstallError)
gem "psych" cannot be uninstalled because it is a default gem