diff --git a/app/controllers/comments_controller.rb b/app/controllers/comments_controller.rb
index 851567c92..474132903 100644
--- a/app/controllers/comments_controller.rb
+++ b/app/controllers/comments_controller.rb
@@ -22,7 +22,7 @@ class CommentsController < ApplicationController
       @discuss = @hack.discusses.new(reply_params)
       @discuss.hidden = false
       @discuss.user_id = current_user.id
-      @discuss.root_id = params[:parent_id]
+      @discuss.root_id = params[:comments][:parent_id]
       @discuss.save!
     rescue Exception => e
       uid_logger_error("reply discuss failed : #{e.message}")
diff --git a/db/migrate/20191223113620_modify_task_pass_for_challenges.rb b/db/migrate/20191223113620_modify_task_pass_for_challenges.rb
new file mode 100644
index 000000000..097892ac5
--- /dev/null
+++ b/db/migrate/20191223113620_modify_task_pass_for_challenges.rb
@@ -0,0 +1,6 @@
+class ModifyTaskPassForChallenges < ActiveRecord::Migration[5.2]
+  def change
+    challenge = Challenge.find(6917)
+    challenge.update_attribute(:task_pass, challenge.gsub("", "").gsub("rac", "\frac"))
+  end
+end