Jekyll comes with a built-in live reload feature to help you preview the change as you make a change to your codes. I encountered an error after running bundle update recently, and it turns out the fix is straightforward.
You can resolve most of the errors by updating affected gems to the latest version.1 However, EventMachine is not exactly being actively maintained, so we don’t always receive the latest version if you’re using RubyGems.org as the source for your Gemfile.
You can fix the error by updating the eventmachine gem source to the official GitHub repository. Here is the line you want to paste into the Gemfile.
gem 'eventmachine', github: 'eventmachine/eventmachine'
After that, you can run bundle update to fetch the latest version of every gem in your Jekyll project.
Sometimes you want to revert to the older version if the latest version is the cause of the errors. Check out the official page to learn more about Gemfile. ↩