How to build task 'assets:precompile'
This is most likely due your config/application.rb not requiring rails/all (the default), but some custom requires.
To resolve this, add the following to config/application.rb:
require 'sprockets/railtie'
I know this is an old post but I thought it might help someone (probably my future self) if I added this to the answers.
add to Capfile (or deploy.rb)
load 'deploy/assets'add this to application.rb
require 'sprockets/railtie'
I think that it might be because you aren't requiring the asset gems in production. By default rails expects that you are pre-compiling your assets in production. Change this in config/application.rb:
Comment out this line:
Bundler.require *Rails.groups(:assets => %w(development test))
And uncomment this line:
Bundler.require(:default, :assets, Rails.env)