diff --git a/addons/project/models/project_task.py b/addons/project/models/project_task.py
index 9af5933e743..931c46637d8 100644
--- a/addons/project/models/project_task.py
+++ b/addons/project/models/project_task.py
@@ -1401,7 +1401,7 @@ class Task(models.Model):
         children = self.child_ids
         if not children:
             return self.env['project.task']
-        return children + children._get_all_subtasks()
+        return children + children._get_subtasks_recursively()
 
     def action_open_parent_task(self):
         return {