Heroku does NOT compile files under assets pipelines in Rails 4
Heroku's asset plugins no longer work since Rails 4 does not support plugins. You need to use Heroku's asset gems instead. Place this in your Gemfile:
group :production do gem 'rails_log_stdout', github: 'heroku/rails_log_stdout' gem 'rails3_serve_static_assets', github: 'heroku/rails3_serve_static_assets'endFollow Heroku's guide on getting started with Rails 4.
Update (07/22/2013): Heroku now supplies a different gem to precompile assets.
group :production do gem 'rails_12factor'end
You need to config Rails to serve static assets in production: config/environments/production.rb
SampleApp::Application.configure do . . . config.serve_static_assets = true . . .end
UPDATE:
In Rails 4 is deprecated, and has been changed by:
config.serve_static_files = true
Since rails 4 replaced manifest.yml with manifest-(fingerprint).json, you'll want to enable static asset serving.
From Getting Started with Rails 4.x on Heroku:
gem 'rails_12factor', group: :productionthen
bundle installand, finally,
git push herokuFixed the issue for me. Hope this helps!