diff --git a/db/migrate/20200102030945_modify_course_group_for_courses.rb b/db/migrate/20200102030946_modify_course_group_for_courses.rb
similarity index 86%
rename from db/migrate/20200102030945_modify_course_group_for_courses.rb
rename to db/migrate/20200102030946_modify_course_group_for_courses.rb
index 6e71af35b..e36bc9e0b 100644
--- a/db/migrate/20200102030945_modify_course_group_for_courses.rb
+++ b/db/migrate/20200102030946_modify_course_group_for_courses.rb
@@ -4,7 +4,9 @@ class ModifyCourseGroupForCourses < ActiveRecord::Migration[5.2]
     ActiveRecord::Base.transaction do
       groups.each do |g|
         CourseGroup.where(name: g.name).where.not(id: g.id).each do |cg|
-          cg.course_members.update_all(course_group_id: g.id)
+          cg.course_members.each do |cm|
+            cm.update_attributes!(course_group_id: g.id)
+          end
           cg.exercise_group_settings.update_all(course_group_id: g.id)
           cg.attachment_group_settings.update_all(course_group_id: g.id)
           cg.homework_group_reviews.update_all(course_group_id: g.id)