bundle exec jekyll serve > Conflict: The following destination is shared by multiple files

Question

Environment

• Windows 10
• ruby 3.0.0p0
• jekyll 4.2.0
• bundler

Steps to get here

• installed ruby and jekyll using instructions: https://jekyllrb.com/docs/installation/windows/#installation-via-rubyinstaller
• cloned existing jekyll repository (uses minimal mistakes theme)
• successfully executed bundle update to update all the dependencies.
• manually installed wdm

Gemfile looks like this:

source "https://rubygems.org"
gemspec
gem 'wdm', '>= 0.1.0' if Gem.win_platform?

Issue

jekyll serve and bundle exec jekyll serve commands fail with the following error:

$ bundle exec jekyll serve
Configuration file: C:/Users/linds/ueducateus-website/_config.yml
Source: C:/Users/linds/ueducateus-website
Destination: C:/Users/linds/ueducateus-website/_site
Incremental build: disabled. Enable with --incremental
Generating...
Jekyll Feed: Generating feed for posts
Conflict: The following destination is shared by multiple files.
The written file may end up with unexpected contents.
C:/Users/linds/ueducateus-website/_site/index.html
- index.html
- index.html
- index.html
- index.html
- index.html

done in 1.511 seconds.
Auto-regeneration: enabled for 'C:/Users/linds/ueducateus-website'
------------------------------------------------
Jekyll 4.2.0 Please append `--trace` to the `serve` command
for any additional information or backtrace.
------------------------------------------------
C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/jekyll-4.2.0/lib/jekyll/commands/serve/servlet.rb:3:in `require': cannot load such file -- webrick (LoadError)
from C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/jekyll-4.2.0/lib/jekyll/commands/serve/servlet.rb:3:in `<top (required)>'
from C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/jekyll-4.2.0/lib/jekyll/commands/serve.rb:179:in `require_relative'
from C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/jekyll-4.2.0/lib/jekyll/commands/serve.rb:179:in `setup'
from C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/jekyll-4.2.0/lib/jekyll/commands/serve.rb:100:in `process'
from C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/jekyll-4.2.0/lib/jekyll/command.rb:91:in `block in process_with_graceful_fail'
from C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/jekyll-4.2.0/lib/jekyll/command.rb:91:in `each'
from C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/jekyll-4.2.0/lib/jekyll/command.rb:91:in `process_with_graceful_fail'
from C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/jekyll-4.2.0/lib/jekyll/commands/serve.rb:86:in `block (2 levels) in init_with_program'
from C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/mercenary-0.4.0/lib/mercenary/command.rb:221:in `block in execute'
from C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/mercenary-0.4.0/lib/mercenary/command.rb:221:in `each'
from C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/mercenary-0.4.0/lib/mercenary/command.rb:221:in `execute'
from C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/mercenary-0.4.0/lib/mercenary/program.rb:44:in `go'
from C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/mercenary-0.4.0/lib/mercenary.rb:21:in `program'
from C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/jekyll-4.2.0/exe/jekyll:15:in `<top (required)>'
from C:/Ruby30-x64/bin/jekyll:23:in `load'
from C:/Ruby30-x64/bin/jekyll:23:in `<main>'

Additional

• Site builds successfully on Ubuntu 18.04, with Ruby 2.5.1 and Jekyll 4.0
• Unfortunately for handover, the site files need to be on Windows
• This issue could be related to https://github.com/kubevirt/kubevirt.github.io/issues/665
• Have run jekyll serve --trace but results are the same

Answer 1

It seems webrick does not come bundled with ruby 3.0. Check this jekyll github issue.

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

You have two options

1. Downgrade to ruby 2.5 as you have on ubuntu OR
2. Add gem "webrick" in Gemfile.