diff --git a/app/interfaces/api/entities/document.rb b/app/interfaces/api/entities/document.rb
index 3b3a4280a7..8b25df0ced 100644
--- a/app/interfaces/api/entities/document.rb
+++ b/app/interfaces/api/entities/document.rb
@@ -9,19 +9,19 @@ class Document < BaseEntity
       private
 
       def attachment
-        object.is_a?(ActiveStorage::Attachment) ? object : object.attachment
+        object.is_a?(ActiveStorage::Attachment) ? object : object.attachment.first
       end
 
       def url
-        attachment.blob.url(disposition: 'attachment') if attachment.attached?
+        attachment.first.blob.url(disposition: 'attachment') if attachment.first.attached?
       end
 
       def file_name
-        attachment.filename if attachment.attached?
+        attachment.first.filename if attachment.first.attached?
       end
 
       def size
-        attachment.byte_size if attachment.attached?
+        attachment.first.byte_size if attachment.first.attached?
       end
     end
   end
diff --git a/app/presenters/message_presenter.rb b/app/presenters/message_presenter.rb
index ce9604efaa..b2481885c7 100644
--- a/app/presenters/message_presenter.rb
+++ b/app/presenters/message_presenter.rb
@@ -8,7 +8,7 @@ def sender_is_a?(klass)
   def body
     h.tag.div do
       h.concat(simple_format(message.body))
-      attachment_field if message.attachment.present?
+      attachment_field if message.attachment.first.present?
     end
   end