ActiveAdmin 0.4.3 Rails 3.2.3升级错误

I've upgraded ActiveAdmin from 0.2.2 to 0.4.3 and Rails from 3.0.0 to 3.2.3. I called "rails generate active_admin:assets" as part of the ActiveAdmin upgrade process. I get the error below when I try to access the ActiveAdmin root directory (https://localhost:3000/admin). Any help would be greatly appreciated. I've upgraded ActiveAdmin from 0.2.2 to 0.4.3 a