Merge pull request #26297 from ledermann/patch-1

Errors#add_on_blank: Fix typo in deprecation message

activemodel/lib/active_model/errors.rb

@@ -372,7 +372,7 @@ def add_on_blank(attributes, options = {})
 
         To achieve the same use:
 
-          errors.add(attribute, :empty, options) if value.blank?
+          errors.add(attribute, :blank, options) if value.blank?
       MESSAGE
 
       Array(attributes).each do |attribute|