diff --git a/mem0/vector_stores/valkey.py b/mem0/vector_stores/valkey.py
index 0688a1288..189285539 100644
--- a/mem0/vector_stores/valkey.py
+++ b/mem0/vector_stores/valkey.py
@@ -299,13 +299,8 @@ class ValkeyDB(VectorStoreBase):
                 # Create the key for the hash
                 key = f"{self.prefix}:{id}"
 
-                # Check for required fields and provide defaults if missing
-                if "data" not in payload:
-                    # Silently use default value for missing 'data' field
-                    pass
-
-                # Ensure created_at is present
-                if "created_at" not in payload:
+                # Default created_at when missing or None to current time
+                if not payload.get("created_at"):
                     payload["created_at"] = datetime.now(pytz.timezone(self.timezone)).isoformat()
 
                 # Prepare the hash data
@@ -499,13 +494,8 @@ class ValkeyDB(VectorStoreBase):
         try:
             key = f"{self.prefix}:{vector_id}"
 
-            # Check for required fields and provide defaults if missing
-            if "data" not in payload:
-                # Silently use default value for missing 'data' field
-                pass
-
-            # Ensure created_at is present
-            if "created_at" not in payload:
+            # Default created_at when missing or None to current time
+            if not payload.get("created_at"):
                 payload["created_at"] = datetime.now(pytz.timezone(self.timezone)).isoformat()
 
             # Prepare the hash data
@@ -521,7 +511,7 @@ class ValkeyDB(VectorStoreBase):
                 hash_data["embedding"] = np.array(vector, dtype=np.float32).tobytes()
 
             # Add updated_at if available
-            if "updated_at" in payload:
+            if payload.get("updated_at"):
                 hash_data["updated_at"] = int(datetime.fromisoformat(payload["updated_at"]).timestamp())
 
             # Add optional fields
diff --git a/tests/vector_stores/test_valkey.py b/tests/vector_stores/test_valkey.py
index 769f511d4..b42a54848 100644
--- a/tests/vector_stores/test_valkey.py
+++ b/tests/vector_stores/test_valkey.py
@@ -158,6 +158,32 @@ def test_insert_handles_missing_created_at(valkey_db, mock_valkey_client):
     assert "created_at" in kwargs["mapping"]  # Should be added automatically
 
 
+def test_insert_and_update_with_none_timestamps(valkey_db, mock_valkey_client):
+    """Regression: a None timestamp must not crash insert() or update().
+
+    A None created_at falls back to now and a None updated_at is skipped, so
+    neither reaches fromisoformat() which only accepts a str.
+    """
+    vector = np.random.rand(1536).tolist()
+
+    valkey_db.insert(
+        vectors=[vector],
+        payloads=[{"hash": "h", "data": "d", "created_at": None, "updated_at": None}],
+        ids=["id1"],
+    )
+    _, insert_kwargs = mock_valkey_client.hset.call_args
+    assert isinstance(insert_kwargs["mapping"]["created_at"], int)
+
+    valkey_db.update(
+        vector_id="id1",
+        vector=vector,
+        payload={"hash": "h", "data": "d", "created_at": None, "updated_at": None},
+    )
+    _, update_kwargs = mock_valkey_client.hset.call_args
+    assert isinstance(update_kwargs["mapping"]["created_at"], int)
+    assert "updated_at" not in update_kwargs["mapping"]
+
+
 def test_delete(valkey_db, mock_valkey_client):
     """Test deleting a vector."""
     # Call delete