diff --git a/BackEnd/src/main/java/studycave/studycaverestservice/model/studyGroup/GroupService.java b/BackEnd/src/main/java/studycave/studycaverestservice/model/studyGroup/GroupService.java
index 3fcd41f..3505b96 100644
--- a/BackEnd/src/main/java/studycave/studycaverestservice/model/studyGroup/GroupService.java
+++ b/BackEnd/src/main/java/studycave/studycaverestservice/model/studyGroup/GroupService.java
@@ -406,7 +406,8 @@ public class GroupService {
                     test.setStatus("UNVERIFIED");
                 }
                 test.setGroup(group);
-                this.testRepository.save(test);
+                test.setActivity(new ArrayList<>());
+                test = this.testRepository.save(test);
                 this.userActivityService.saveActivity("addedResource", 0, null, user, null, group, null, null, test);
             });
         }
diff --git a/BackEnd/src/main/java/studycave/studycaverestservice/model/test/Test.java b/BackEnd/src/main/java/studycave/studycaverestservice/model/test/Test.java
index ff12c5b..ad36c36 100644
--- a/BackEnd/src/main/java/studycave/studycaverestservice/model/test/Test.java
+++ b/BackEnd/src/main/java/studycave/studycaverestservice/model/test/Test.java
@@ -57,7 +57,7 @@ public class Test {
     private StudyGroup group;
 
     @OneToMany(fetch = FetchType.LAZY, mappedBy = "test", cascade = CascadeType.ALL)
-    private List<UserActivity> activity;
+    private List<UserActivity> activity = new ArrayList<>();
 
     public void setAddDate() {
         java.util.Date utilDate = new java.util.Date();
diff --git a/BackEnd/src/main/java/studycave/studycaverestservice/model/userActivity/UserActivity.java b/BackEnd/src/main/java/studycave/studycaverestservice/model/userActivity/UserActivity.java
index 3076c05..9c0f0c9 100644
--- a/BackEnd/src/main/java/studycave/studycaverestservice/model/userActivity/UserActivity.java
+++ b/BackEnd/src/main/java/studycave/studycaverestservice/model/userActivity/UserActivity.java
@@ -46,7 +46,6 @@ public class UserActivity {
     private Set set;
 
     @ManyToOne
-    @JoinColumn(name = "test_id")
     private Test test;
 
     @ManyToOne