diff --git a/backend/api/main.py b/backend/api/main.py
index 25987de..3498813 100644
--- a/backend/api/main.py
+++ b/backend/api/main.py
@@ -65,8 +65,20 @@ async def get_tribe(name: str):
 
 @app.post("/students", status_code=status.HTTP_201_CREATED, response_model=StudentModel)
 async def post_student(item: StudentModel):
+    if item.id is not None:
+        return JSONResponse(
+            status_code=status.HTTP_409_CONFLICT,
+            content=f"You can't post a student with an id. It is already registrered. Use PUT to modify it.",
+        )
+
     tribe_name = item.tribe_name
-    tribe = tribe_repo.get(tribe_name)
+    try:
+        tribe = tribe_repo.get(tribe_name)
+    except TribeRepositoryError:
+        return JSONResponse(
+            status_code=status.HTTP_409_CONFLICT,
+            content=f"The tribe {tribe_name} does not exists. You can't add a student in it.",
+        )
 
     student = Student(item.name, tribe)
 
diff --git a/backend/repository/tribe_sqlite_repository.py b/backend/repository/tribe_sqlite_repository.py
index b7d2c72..cc2a4e9 100644
--- a/backend/repository/tribe_sqlite_repository.py
+++ b/backend/repository/tribe_sqlite_repository.py
@@ -52,7 +52,7 @@ class TribeSQLiteRepository(AbstractRepository):
         if row:
             return Tribe(*row)
 
-        raise ValueError(f"The tribe {name} does not exists")
+        raise TribeRepositoryError(f"The tribe {name} does not exists")
 
     def list(self) -> list[Tribe]:
         cursor = self.conn.cursor()
diff --git a/tests/e2e/test_api.py b/tests/e2e/test_api.py
index 2ecf119..99922c4 100644
--- a/tests/e2e/test_api.py
+++ b/tests/e2e/test_api.py
@@ -74,15 +74,35 @@ def test_api_post_student():
 
 @pytest.mark.usefixtures("restart_api")
 @pytest.mark.usefixtures("clean_db")
-def test_api_post_student():
+def test_api_post_student_with_id():
     url = config.get_api_url()
     tribe = build_tribes(1)[0]
     requests.post(f"{url}/tribes", json=tribe.to_dict())
 
-    data = {"name": "zart", "tribe_name": tribe.name}
+    data = {"id": "1234", "name": "zart", "tribe_name": tribe.name}
+    requests.post(f"{url}/students", json=data)
     r = requests.post(f"{url}/students", json=data)
 
-    assert r.status_code == 201
-    assert r.json()["name"] == "zart"
-    assert r.json()["tribe_name"] == tribe.name
-    assert r.json()["id"]
+    assert r.status_code == 409
+    assert (
+        r.json()
+        == f"You can't post a student with an id. It is already registrered. Use PUT to modify it."
+    )
+
+
+@pytest.mark.usefixtures("restart_api")
+@pytest.mark.usefixtures("clean_db")
+def test_api_post_student_in_non_existant_tribe():
+    url = config.get_api_url()
+    tribe = build_tribes(1)[0]
+    requests.post(f"{url}/tribes", json=tribe.to_dict())
+
+    data = {"name": "zart", "tribe_name": tribe.name + "_"}
+    requests.post(f"{url}/students", json=data)
+    r = requests.post(f"{url}/students", json=data)
+
+    assert r.status_code == 409
+    assert (
+        r.json()
+        == f"The tribe {tribe.name+'_'} does not exists. You can't add a student in it."
+    )