diff --git a/alembic/versions/58c0e071db99_adds_deleted_user.py b/alembic/versions/58c0e071db99_adds_deleted_user.py
new file mode 100644
index 00000000..1f35cca9
--- /dev/null
+++ b/alembic/versions/58c0e071db99_adds_deleted_user.py
@@ -0,0 +1,58 @@
+"""adds deleted user
+
+Revision ID: 58c0e071db99
+Revises: de396670d10f
+Create Date: 2025-09-15 14:08:25.901703
+
+"""
+
+from alembic import op
+from submodules.model import DELETED_USER_ID, DELETED_USER_EMAIL
+
+# revision identifiers, used by Alembic.
+revision = "58c0e071db99"
+down_revision = "de396670d10f"
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    connection = op.get_bind()
+    insert_deleted_user_sql = f"""
+insert into	public."user" (
+	id,
+	organization_id,
+	"role",
+	last_interaction,
+	language_display,
+	email,
+	verified,
+	created_at,
+	metadata_public,
+	sso_provider,
+	use_new_cognition_ui,
+	oidc_identifier
+) values (
+	'{DELETED_USER_ID}', 
+	NULL, 
+	NULL, 
+	NULL, 
+	NULL, 
+	'{DELETED_USER_EMAIL}', 
+	false, 
+	NOW(),
+	NULL, 
+	NULL, 
+	false, 
+	null
+);
+"""
+    connection.execute(insert_deleted_user_sql)
+
+
+def downgrade():
+    connection = op.get_bind()
+    delete_deleted_user_sql = f"""
+delete from public."user" where id = '{DELETED_USER_ID}';
+"""
+    connection.execute(delete_deleted_user_sql)
diff --git a/controller/auth/kratos.py b/controller/auth/kratos.py
index a93c09ef..fc295bfd 100644
--- a/controller/auth/kratos.py
+++ b/controller/auth/kratos.py
@@ -8,6 +8,7 @@
 from urllib.parse import quote
 
 from controller.user import manager
+from submodules.model import DELETED_USER_ID, DELETED_USER_EMAIL
 
 
 logging.basicConfig(level=logging.INFO)
@@ -75,6 +76,24 @@ def __refresh_identity_cache(update_db_users: bool = True) -> None:
     else:
         KRATOS_IDENTITY_CACHE = {}
 
+    # dummy identity for deleted users
+    # this identity should not be in kratos but in db only
+    # note that deleted users usually SET_NULL on foreign keys so the id is not in use anymore
+    KRATOS_IDENTITY_CACHE[DELETED_USER_ID] = {
+        "identity": {
+            "id": DELETED_USER_ID,
+            "traits": {
+                "email": DELETED_USER_EMAIL,
+                "name": {"first": "Deleted", "last": "User"},
+            },
+        },
+        "simple": {
+            "id": DELETED_USER_ID,
+            "mail": DELETED_USER_EMAIL,
+            "firstName": "Deleted",
+            "lastName": "User",
+        },
+    }
     if update_db_users:
         manager.migrate_kratos_users()
 
diff --git a/controller/monitor/manager.py b/controller/monitor/manager.py
index f4bdd43b..8d7a117d 100644
--- a/controller/monitor/manager.py
+++ b/controller/monitor/manager.py
@@ -2,6 +2,7 @@
 from submodules.model.business_objects import monitor as task_monitor
 from controller.auth import kratos
 from submodules.model.util import sql_alchemy_to_dict
+from submodules.model import DELETED_USER_ID
 
 
 def monitor_all_tasks(page: int, limit: int) -> List[Any]:
@@ -9,6 +10,7 @@ def monitor_all_tasks(page: int, limit: int) -> List[Any]:
     tasks_dict = sql_alchemy_to_dict(tasks)
     user_ids = {str(t["created_by"]) for t in tasks}  # set comprehension
     name_lookup = {u_id: kratos.resolve_user_name_by_id(u_id) for u_id in user_ids}
+    name_lookup[DELETED_USER_ID] = {"first": "Deleted", "last": "User"}
 
     for t in tasks_dict:
         created_by_first_last = name_lookup[str(t["created_by"])]
diff --git a/controller/user/manager.py b/controller/user/manager.py
index dfdc4363..1c1e9e39 100644
--- a/controller/user/manager.py
+++ b/controller/user/manager.py
@@ -1,5 +1,5 @@
 from typing import Dict, Optional, Any
-from submodules.model import User, daemon, enums
+from submodules.model import User, daemon, enums, DELETED_USER_ID
 from submodules.model.business_objects import user, general
 from controller.auth import kratos
 from submodules.model.exceptions import EntityNotFoundException
@@ -138,7 +138,11 @@ def __migrate_kratos_users():
 
     for user_database in users_database:
         user_id = str(user_database.id)
-        if user_id not in users_kratos or users_kratos[user_id] is None:
+        if (
+            user_id not in users_kratos
+            or users_kratos[user_id] is None
+            or user_id == DELETED_USER_ID
+        ):
             continue
         user_identity = users_kratos[user_id]["identity"]
         if user_database.email != user_identity["traits"]["email"]:
diff --git a/submodules/model b/submodules/model
index 04dcb6cf..13f55cbc 160000
--- a/submodules/model
+++ b/submodules/model
@@ -1 +1 @@
-Subproject commit 04dcb6cf25cd374b9662f32f95880e165c62b6af
+Subproject commit 13f55cbcc547209a4511f8bc077d8f19ca920914