Bundle exec jekyll serve error

  question, ruby

![当执行bundle exec Jekyll serve ,提示如图

After a project has been decompressed by fork on GitHub, it enters the decompressed project directory through dos command box. When bundle exec Jekyll serve is executed, the above-mentioned situation appears, and the _site folder and some of its contents appear in the project.
However, the localhost:4000 site cannot be found in the browser. Because the execution command (bundle exec Jekyll serve) prompts Jekyll 3.2.1 error, I guess Jekyll’s problem, but because I have not learned ruby before, I am not sure how to solve this problem. Therefore, if anyone has encountered the problem I described, please comment. Grateful

The following is my configuration environment
My environment is: win10
Ruby has successfully installed version 2.0.0p64
RubyDevkit successfully configured
Bundle installed successfully, version 1.14.4
Jekyll version 3.4.0

Execution is required before execution:

bundle install