It looks like you don't have kramdown-parser-gfm

[jrichardsz]

I got this error:

Configuration file: /usr/src/app/_config.yml
       Deprecation: The 'gems' configuration option has been renamed to 'plugins'. Please update your config file accordingly.
            Source: /usr/src/app
       Destination: /usr/src/app/_site
 Incremental build: disabled. Enable with --incremental
      Generating... 
  Dependency Error: Yikes! It looks like you don't have kramdown-parser-gfm 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 -- kramdown-parser-gfm' If you run into trouble, you can find helpful resources at https://jekyllrb.com/help/! 
  Conversion error: Jekyll::Converters::Markdown encountered an error while converting '_posts/2017-11-12-question-1.md':
                    kramdown-parser-gfm
             ERROR: YOUR SITE COULD NOT BE BUILT:
                    ------------------------------------
                    kramdown-parser-gfm

I fixed with:

• delete the Gemfile.lock file
• go to gem file add gem "kramdown-parser-gfm" at the top