diff --git a/app/controllers/exercises_controller.rb b/app/controllers/exercises_controller.rb
index 9a46aa09b..4b96afc85 100644
--- a/app/controllers/exercises_controller.rb
+++ b/app/controllers/exercises_controller.rb
@@ -1546,7 +1546,7 @@ class ExercisesController < ApplicationController
     @exercise_ques_shixun_count = exercise_ques_shixun.size
     @exercise_ques_shixun_scores = exercise_ques_shixun.pluck(:question_score).sum
 
-    @exercise_questions = @exercise_questions.includes(:exercise_choices,:exercise_shixun_challenges,:exercise_answers,:exercise_shixun_answers,:exercise_answer_comments,:exercise_standard_answers)
+    @exercise_questions = @exercise_questions&.includes(:exercise_choices,:exercise_shixun_challenges,:exercise_answers,:exercise_shixun_answers,:exercise_answer_comments,:exercise_standard_answers)
 
   end
 
diff --git a/app/services/exercise_user_pdf_service.rb b/app/services/exercise_user_pdf_service.rb
index 63fbb5a1d..22804092e 100644
--- a/app/services/exercise_user_pdf_service.rb
+++ b/app/services/exercise_user_pdf_service.rb
@@ -81,7 +81,7 @@ class ExerciseUserPdfService
     @exercise_ques_shixun_count = exercise_ques_shixun.size
     @exercise_ques_shixun_scores = exercise_ques_shixun.pluck(:question_score).sum
 
-    @exercise_questions = @exercise_questions.includes(:exercise_choices,:exercise_shixun_challenges,:exercise_answers,:exercise_shixun_answers,:exercise_answer_comments,:exercise_standard_answers)
+    @exercise_questions = @exercise_questions&.includes(:exercise_choices,:exercise_shixun_challenges,:exercise_answers,:exercise_shixun_answers,:exercise_answer_comments,:exercise_standard_answers)
     get_each_student_exercise(exercise.id,@exercise_questions,@ex_user_user.id)
 
   end