我遇到了同样的问题，并且能够像在Heroku Cedar上的Rails 3.1+ Asset Pipeline中提到的那样，在推送到Heroku之前通过本地编译资产来解决此问题。

RAILS_ENV=production bundle exec rake assets:precompile

我还尝试了Itecedors建议，该建议也有效：

While precompiling assets, in Rails 3.1.1 and up, you can prevent initializing
your application and connecting to the database by ensuring that the following 
line is in your > config/application.rb:

config.assets.initialize_on_precompile = false

在Heroku上，我遇到了同样的错误，而谷歌搜索并没有帮助我找到问题，所以我想我将添加到该问题中的内容添加到搜索中，因为它首先出现在搜索中。

问题不在于此错误，而是在将代码推送到Heroku时的较小错误。列出宝石之后，这些行将我带到了答案的道路上：

Running: rake assets:precompile
rake aborted!
Tasks: TOP => environment
(See full trace by running task with --trace)
Precompiling assets failed, enabling runtime asset compilation
Injecting rails31_enable_runtime_asset_compilation
Please see this article for troubleshooting help:
http://devcenter.heroku.com/articles/rails31_heroku_cedar#troubleshooting

我刚刚在Heroku上配置Redis，所以我知道问题一定与这些更改有关。在该网址，我发现了这一点：

While precompiling assets, in Rails 3.1.1 and up, you can prevent initializing your application and connecting to the database by ensuring that the following line is in your > config/application.rb:

config.assets.initialize_on_precompile = false

Adding the on_precompile = false line fixed all the errors, including the original one in this question.