Jekyll serve fails on Ruby 3.0

[argilo]

My Environment

Software	Version(s)
Operating System	Ubuntu 20.04
Ruby	3.0.0
jekyll	4.2.0
github-pages	No

---

Expected Behaviour

bundle exec jekyll serve runs on Ruby 3.0.

Current Behavior

bundle exec jekyll serve fails with the following stack trace:

/home/argilo/.gem/ruby/3.0.0/gems/jekyll-4.2.0/lib/jekyll/commands/serve/servlet.rb:3:in `require': cannot load such file -- webrick (LoadError)
	from /home/argilo/.gem/ruby/3.0.0/gems/jekyll-4.2.0/lib/jekyll/commands/serve/servlet.rb:3:in `<top (required)>'
	from /home/argilo/.gem/ruby/3.0.0/gems/jekyll-4.2.0/lib/jekyll/commands/serve.rb:179:in `require_relative'
	from /home/argilo/.gem/ruby/3.0.0/gems/jekyll-4.2.0/lib/jekyll/commands/serve.rb:179:in `setup'
	from /home/argilo/.gem/ruby/3.0.0/gems/jekyll-4.2.0/lib/jekyll/commands/serve.rb:100:in `process'
	from /home/argilo/.gem/ruby/3.0.0/gems/jekyll-4.2.0/lib/jekyll/command.rb:91:in `block in process_with_graceful_fail'
	from /home/argilo/.gem/ruby/3.0.0/gems/jekyll-4.2.0/lib/jekyll/command.rb:91:in `each'
	from /home/argilo/.gem/ruby/3.0.0/gems/jekyll-4.2.0/lib/jekyll/command.rb:91:in `process_with_graceful_fail'
	from /home/argilo/.gem/ruby/3.0.0/gems/jekyll-4.2.0/lib/jekyll/commands/serve.rb:86:in `block (2 levels) in init_with_program'
	from /home/argilo/.gem/ruby/3.0.0/gems/mercenary-0.4.0/lib/mercenary/command.rb:221:in `block in execute'
	from /home/argilo/.gem/ruby/3.0.0/gems/mercenary-0.4.0/lib/mercenary/command.rb:221:in `each'
	from /home/argilo/.gem/ruby/3.0.0/gems/mercenary-0.4.0/lib/mercenary/command.rb:221:in `execute'
	from /home/argilo/.gem/ruby/3.0.0/gems/mercenary-0.4.0/lib/mercenary/program.rb:44:in `go'
	from /home/argilo/.gem/ruby/3.0.0/gems/mercenary-0.4.0/lib/mercenary.rb:21:in `program'
	from /home/argilo/.gem/ruby/3.0.0/gems/jekyll-4.2.0/exe/jekyll:15:in `<top (required)>'
	from /home/argilo/.gem/ruby/3.0.0/bin/jekyll:23:in `load'
	from /home/argilo/.gem/ruby/3.0.0/bin/jekyll:23:in `<top (required)>'
	from /home/argilo/.rubies/ruby-3.0.0/lib/ruby/3.0.0/bundler/cli/exec.rb:63:in `load'
	from /home/argilo/.rubies/ruby-3.0.0/lib/ruby/3.0.0/bundler/cli/exec.rb:63:in `kernel_load'
	from /home/argilo/.rubies/ruby-3.0.0/lib/ruby/3.0.0/bundler/cli/exec.rb:28:in `run'
	from /home/argilo/.rubies/ruby-3.0.0/lib/ruby/3.0.0/bundler/cli.rb:497:in `exec'
	from /home/argilo/.rubies/ruby-3.0.0/lib/ruby/3.0.0/bundler/vendor/thor/lib/thor/command.rb:27:in `run'
	from /home/argilo/.rubies/ruby-3.0.0/lib/ruby/3.0.0/bundler/vendor/thor/lib/thor/invocation.rb:127:in `invoke_command'
	from /home/argilo/.rubies/ruby-3.0.0/lib/ruby/3.0.0/bundler/vendor/thor/lib/thor.rb:392:in `dispatch'
	from /home/argilo/.rubies/ruby-3.0.0/lib/ruby/3.0.0/bundler/cli.rb:30:in `dispatch'
	from /home/argilo/.rubies/ruby-3.0.0/lib/ruby/3.0.0/bundler/vendor/thor/lib/thor/base.rb:485:in `start'
	from /home/argilo/.rubies/ruby-3.0.0/lib/ruby/3.0.0/bundler/cli.rb:24:in `start'
	from /home/argilo/.rubies/ruby-3.0.0/lib/ruby/gems/3.0.0/gems/bundler-2.2.3/libexec/bundle:49:in `block in <top (required)>'
	from /home/argilo/.rubies/ruby-3.0.0/lib/ruby/3.0.0/bundler/friendly_errors.rb:130:in `with_friendly_errors'
	from /home/argilo/.rubies/ruby-3.0.0/lib/ruby/gems/3.0.0/gems/bundler-2.2.3/libexec/bundle:37:in `<top (required)>'
	from /home/argilo/.rubies/ruby-3.0.0/bin/bundle:23:in `load'
	from /home/argilo/.rubies/ruby-3.0.0/bin/bundle:23:in `<main>'

This happens because webrick is no longer a bundled gem in Ruby 3.0. From https://www.ruby-lang.org/en/news/2020/12/25/ruby-3-0-0-released/:

The following libraries are no longer bundled gems or standard libraries. Install the corresponding gems to use these features.

• sdbm
• webrick
• net-telnet
• xmlrpc

Adding gem "webrick" to my Gemfile solves the problem, but Jekyll should include it in its gemspec.

[argilo]

I think you want bundle add webrick.

[ianbstewart]

+1 for the issue with webrick, I faced a similar problem when running jekyll serve in a different context than the one described here.

[ichaiwut]

@argilo Thanks, you really saved my day.

[jaegpark]

@argilo you're a lifesaver thank you so much!

[dbubenheim]

Thanks, adding webrick worked for me.

[shafiemukhre]

Thank you @argilo, $bundle add webrick works!

[ksilz]

Thank you @argilo!

[Hadrien-Montanelli]

webrick did the job for me too - thanks @argilo.

[tc6899]

Big thanks from me as well @argilo
You've allowed me to stop working before midnight

[chrissimpkins]

I don't have experience with Ruby dependency management. Does adding the webrick gem definition to a Jekyll site's Gemfile cause issues in ruby < 3.0? Is the optimal approach to address this issue documentation that users on ruby 3.0+ should use bundle add webrick before they use jekyll serve?

[argilo]

Does adding the webrick gem definition to a Jekyll site's Gemfile cause issues in ruby < 3.0?

No, it does not.

[chrissimpkins]

Tyvm!

[yegor256]

@argilo I have the same problem with Ruby 3.2.1 on macOS. Adding webrick to Gemfile doesn't help. Jekyll 3.6.3. Upgrading to Jekyl 4.3.2 solved the problem.

[paraisoreavido]

I think you want bundle add webrick.

[nxtexploit]

I was digging for 2 hours then finally it worked. thank you 😄

[rushingfox]

I think you want bundle add webrick.

It works for me!

[wcgordon1]

I added webrick.

Still getting the following error:

Jekyll 4.3.2 Please append --trace to the serve command
for any additional information or backtrace.

Going to take a break before I mess anything up further. Posting if anyone has a solution.

If/when I figure out the issue I'll reply to this comment.

Going for a walk. Thanks!