diff --git a/backend/src/main/java/core/entities/timemanager/TaskSerieItem.java b/backend/src/main/java/core/entities/timemanager/TaskSerieItem.java
index 46728fa..3160a78 100644
--- a/backend/src/main/java/core/entities/timemanager/TaskSerieItem.java
+++ b/backend/src/main/java/core/entities/timemanager/TaskSerieItem.java
@@ -14,7 +14,7 @@ public class TaskSerieItem {
     @JoinColumn(referencedColumnName = "taskSerieID")
     private TaskSerie taskSerie;
 
-    @OneToOne(cascade = CascadeType.ALL)
+    @OneToOne
     @JoinColumn(name = "task_id")
     private Task task;
 
diff --git a/backend/src/main/java/core/services/TaskSeriesService.java b/backend/src/main/java/core/services/TaskSeriesService.java
index efac5cb..65fa3b1 100644
--- a/backend/src/main/java/core/services/TaskSeriesService.java
+++ b/backend/src/main/java/core/services/TaskSeriesService.java
@@ -35,12 +35,11 @@ public class TaskSeriesService {
         }
 
         List<Task> taskList = new ArrayList<>();
-        taskList.add(rootTask);
-        LocalDate currentTaskDate = rootTask.getStartDate().plusDays(taskRepeatInfo.getOffset());
         TaskSerie taskSerie = new TaskSerie();
-
         TaskSerieItem rootItem = taskSerie.addTask(rootTask);
         rootTask.setTaskSerieItem(rootItem);
+
+        LocalDate currentTaskDate = rootTask.getStartDate().plusDays(taskRepeatInfo.getOffset());
         int index = 2;
         while(currentTaskDate.isBefore(taskRepeatInfo.getEndingDate())) {
             Task task = Task.cloneTask(rootTask);
@@ -69,7 +68,11 @@ public class TaskSeriesService {
         TaskSerie taskSerie = task.getTaskSerieItem().getTaskSerie();
         task.setTaskSerieItem(null);
         taskSerieItemRepository.delete(item);
-        if(taskSerie.getTasks().size() <= 1) {
+        if(taskSerie.getTasks().isEmpty()) {
+            for(TaskSerieItem taskSerieItem : taskSerie.getTasks()) {
+                taskSerieItem.setTaskSerie(null);
+            }
+            taskSerie.getTasks().clear();
             taskSeriesRepository.delete(taskSerie);
         }
     }