diff --git a/app/tasks/exercise_publish_task.rb b/app/tasks/exercise_publish_task.rb
index 387a834f1..4c8ee39e8 100644
--- a/app/tasks/exercise_publish_task.rb
+++ b/app/tasks/exercise_publish_task.rb
@@ -44,7 +44,7 @@ class ExercisePublishTask
     end
 
     # 分组设置发布时间的测验
-    exercise_group_settings = ExerciseGroupSetting.where("publish_time < ? and publish_time > ?", Time.now + 1800, Time.now - 1800)
+    exercise_group_settings = ExerciseGroupSetting.where("publish_time < ? and publish_time > ?", Time.now + 900, Time.now - 900)
     exercise_group_settings.each do |exercise_group|
       exercise = exercise_group.exercise
       if exercise.present?
@@ -70,12 +70,12 @@ class ExercisePublishTask
     Rails.logger.info("log--------------------------------exercise_end start")
     puts "--------------------------------exercise_end start"
     # 1。统一设置的试卷
-    exercises = Exercise.includes(:exercise_users,:exercise_questions).where("exercise_status = 2 AND unified_setting = true AND end_time <= ?",Time.now)
+    exercises = Exercise.includes(:exercise_users,:exercise_questions).where("exercise_status = 2 AND unified_setting = true AND end_time <= ?",Time.now + 900)
     exercises.each do |exercise|
       ex_type = exercise.exercise_questions.pluck(:question_type).uniq
       exercise.update_column('exercise_status', 3)
       exercise.exercise_users.each do |exercise_user|
-        if exercise_user.commit_status == 0 && exercise_user.start_at.present?
+        if exercise_user&.commit_status == 0 && exercise_user&.start_at.present?
           s_score = calculate_student_score(exercise, exercise_user.user)[:total_score]
           if ex_type.include?(4)   #是否包含主观题
             subjective_score = exercise_user.subjective_score
@@ -98,7 +98,7 @@ class ExercisePublishTask
     end
 
     # 2.非统一的试卷
-    all_exercises = Exercise.includes(:exercise_group_settings,:exercise_users,:exercise_questions).where("unified_setting = false AND exercise_status = 2 AND end_time > ?",Time.now)
+    all_exercises = Exercise.includes(:exercise_group_settings,:exercise_users,:exercise_questions).where("unified_setting = false AND exercise_status = 2 AND end_time > ?",Time.now + 900)
     exercise_ids = all_exercises.blank? ? "(-1)" : "(" + all_exercises.map(&:id).join(",") + ")"
     ex_group_settings = ExerciseGroupSetting.where("end_time <= '#{Time.now}' and exercise_id in #{exercise_ids}")
     ex_group_settings.each do |exercise_setting|