Ruby on Rails cannot start rails server

I am running an existing project on my laptop locally. Did bundle install, then ran rails server. However, I get the below error. What's causing it and how to fix it so that I can run it properly?

/usr/local/lib/ruby/gems/2.1.0/gems/railties-4.2.3/lib/rails/app_rails_loader.rb:39: warning: Insecure world writable dir /opt in PATH, mode 040777
/usr/local/Cellar/ruby/2.1.4/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require': cannot load such file -- /Users/project/config/boot (LoadError)
    from /usr/local/Cellar/ruby/2.1.4/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
    from script/rails:5:in `<main>'