Compiling assets fails: can't dump anonymous class

[Georg Schlenkhoff]

I am trying to push refinery to Heroku. Using heroku toolbelt or precompiling assets manually fails with:

       ...

       Running: rake assets:precompile

       Connecting to database specified by DATABASE_URL

       Compiled jquery.js  (4ms)  (pid 709)

       Compiled jquery_ujs.js  (0ms)  (pid 709)

       Compiled application.js  (14ms)  (pid 709)

       Warning. Error encountered while saving cache /tmp/build_f2a6157c-b4fe-45b6-a936-3010c4d481f1/tmp/cache/sass/1e2facb516378de3205c3da490c126bf027d99f3/formatting.css.scssc: can't dump anonymous class #<Class:0x007f492ac504e8>

       Compiled refinery/formatting.css  (24ms)  (pid 709)

       Warning. Error encountered while saving cache /tmp/build_f2a6157c-b4fe-45b6-a936-3010c4d481f1/tmp/cache/sass/1e2facb516378de3205c3da490c126bf027d99f3/theme.css.scssc: can't dump anonymous class #<Class:0x007f492ac504e8>

       ...

I tried to downgrade sass-rails to version 3.2.19 as suggsested here. But that fails, too, because another gem is dependent on sass-rails >= 3.2.3.

My Gemfile is as follows:

source 'https://rubygems.org'

ruby '2.0.0'

gem 'rails', '3.2.18'

group :development, :test do

  gem 'sqlite3'

end

group :assets do

  gem 'sass-rails',   '~> 3.2.3'

  gem 'coffee-rails', '~> 3.2.1'

  gem 'uglifier', '>= 1.0.3'

end

gem 'jquery-rails'

# Refinery CMS

gem 'refinerycms', '~> 2.1.0'

# Optionally, specify additional Refinery CMS Extensions here:

gem 'refinerycms-acts-as-indexed', '~> 1.0.0'

#  gem 'refinerycms-blog', '~> 2.1.0'

#  gem 'refinerycms-inquiries', '~> 2.1.0'

#  gem 'refinerycms-search', '~> 2.1.0'

#  gem 'refinerycms-page-images', '~> 2.1.0'

# The Heroku gem allows you to interface with Heroku's API

gem 'heroku'

# Fog allows you to use S3 assets (added for Heroku)

gem 'fog'

# Postgres and 12factor support (added for Heroku)

gem 'pg'

gem 'rails_12factor', group: :production

Anyone can help on that issue?

[Philip Arndt]

Do you have this in your initializers/application config?:

    config.assets.initialize_on_precompile = true