Warning. Error encountered while saving cache … can't dump anonymous class

Question

When app is deployed with capistrano errors occur in production.log.

Compiled signup.css  (30ms)  (pid 31797)
Warning. Error encountered while saving cache /         


        

Answer 1

It is a known bug with the current release of Sass, updating the sass stylesheet will cause the caching error because of the Sprockets importer not serializing correctly. For the bug report see this.

Answer 2

It is a bug in sprockets, but if, like me you are using an older version of Rails (3.2) you may be able to fix the bug by using a different version of sass. This guy was able to get it working with sass 3.1.x: https://github.com/rails/sass-rails/issues/242#issuecomment-66231135

The thread mentioned there gives some good context and an explanation for how to handle solving the issue or working around an inability to upgrade to a much newer, fixed version of sprockets.

Basically, use sass/sass-rails/sprockets from around the time Rails 3.2.x was supported.