• I believe this to be a bug, not a question about using Jekyll.
• I updated to the latest Jekyll (or) if on GitHub Pages to the latest github-pages
• I read the CONTRIBUTION file at https://jekyllrb.com/docs/contributing/

• I am on (or have tested on) Windows 10+

• It was another bug.

My Reproduction Steps

Install Jekyll 3.4.1

gem install Jekyll

Installation worked.

Attempting to build my site (via a PowerShell script) gave this error

Configuration file: C:\dev\www.nichesoftware.co.nz\src/_config.yml
  Dependency Error: Yikes! It looks like you don't have tzinfo or one of its dependencies installed. In order
  to use Jekyll as currently configured, you'll need to install this gem. The full error message from Ruby is:
  'cannot load such file -- tzinfo' If you run into trouble, you can find helpful resources at
  https://jekyllrb.com/help/!

Manual Fix

To work around the issue, I installed tzinfo manually

gem install tzinfo

I then got a different error:

Configuration file: C:\dev\www.nichesoftware.co.nz\src/_config.yml
C:/Ruby23-x64/lib/ruby/gems/2.3.0/gems/tzinfo-1.2.2/lib/tzinfo/data_source.rb:182:in `rescue in create_default_data_source': No source of timezone data could be found. (TZInfo::DataSourceNotFound)
Please refer to http://tzinfo.github.io/datasourcenotfound for help resolving this error.

Fixing this required manual installation of tzinfo-data

gem install tzinfo-data

From what I found online, I only needed this last step because I'm running 64 bit Ruby on Windows

Expectation

The Jekyll gem should reference tzinfo as a dependency, and possibly tzinfo-data as well.

As much as anything else, I'm logging this issue so that someone searching this repo for tzinfo can find a workaround for the issue.

/cc @jekyll/build @jekyll/windows