Kevin Marsh

If you encounter this issue booting up a Mongrel:

$ ./script/server 
/Library/Ruby/Site/1.8/rubygems/custom_require.rb:27:in `gem_original_require': no such file to load -- builder/blankslate (LoadError)
    from /Library/Ruby/Site/1.8/rubygems/custom_require.rb:27:in `require'
    from /Users/kmarsh/Sites/sampleboardportal/vendor/rails/activesupport/lib/active_support/basic_object.rb:3
    from /Library/Ruby/Site/1.8/rubygems/custom_require.rb:27:in `gem_original_require'
    from /Library/Ruby/Site/1.8/rubygems/custom_require.rb:27:in `require'
    from /Users/kmarsh/Sites/sampleboardportal/vendor/rails/activesupport/lib/active_support.rb:29
    from /Users/kmarsh/Sites/sampleboardportal/vendor/rails/railties/lib/commands/server.rb:1:in `require'
    from /Users/kmarsh/Sites/sampleboardportal/vendor/rails/railties/lib/commands/server.rb:1
    from ./script/server:3:in `require'
    from ./script/server:3

...it’s because you’re missing Builder. Try a sudo gem install builder. Fixed the issue for me!