In my Rails 4.2 app, the file uploads stopped working for the model which has following
acts_as_nested_set counter_cache: :children_count, touch: true
Removing this line, the uploads starts working again. I'm managinh content via RailsAdmin using Carrierwave and fog-google gems. File uploads for other models are working fine which uses the same uploader. I can update or create record fine but the image is not being uploaded. It fails without any error.