⚠️ instance variable @versions, @Format, @file, @filename, @cache_id …

…not initialized

lib/carrierwave/processing/mini_magick.rb

@@ -61,6 +61,13 @@ module MiniMagick
         e.message << " (You may need to install the mini_magick gem)"
         raise e
       end
+
+      prepend Module.new {
+        def initialize(*)
+          super
+          @format = nil
+        end
+      }
     end
 
     module ClassMethods

lib/carrierwave/processing/rmagick.rb

@@ -67,6 +67,13 @@ module RMagick
         e.message << " (You may need to install the rmagick gem)"
         raise e
       end
+
+      prepend Module.new {
+        def initialize(*)
+          super
+          @format = nil
+        end
+      }
     end
 
     module ClassMethods

lib/carrierwave/uploader/store.rb

@@ -7,6 +7,15 @@ module Store
       include CarrierWave::Uploader::Configuration
       include CarrierWave::Uploader::Cache
 
+      included do
+        prepend Module.new {
+          def initialize(*)
+            super
+            @file, @filename, @cache_id = nil
+          end
+        }
+      end
+
       ##
       # Override this in your Uploader to change the filename.
       #

lib/carrierwave/uploader/versions.rb

@@ -19,6 +19,13 @@ module Versions
         after :remove, :remove_versions!
         after :retrieve_from_cache, :retrieve_versions_from_cache!
         after :retrieve_from_store, :retrieve_versions_from_store!
+
+        prepend Module.new {
+          def initialize(*)
+            super
+            @versions = nil
+          end
+        }
       end
 
       module ClassMethods