Could not find abstract-1.0.0 in any of the sources (Bundler::GemNotFound)

bundle install --path vendor/cache

run the server again.

You can change this by deleting the cache (folder) in vendor. Do bundle install again and it will do it normally.
original post: http://stackoverflow.com/questions/5920872/ruby-on-rails-3-apache2-phusion-passenger-bundlergemnotfound-exception