diff --git a/backend/open_webui/utils/chat.py b/backend/open_webui/utils/chat.py
index 5ce6fffec..9a9e81033 100644
--- a/backend/open_webui/utils/chat.py
+++ b/backend/open_webui/utils/chat.py
@@ -316,6 +316,10 @@ async def chat_completed(request: Request, form_data: dict, user: Any):
         models = request.app.state.MODELS
 
     data = form_data
+
+    if not data.get('id'):
+        raise Exception('Missing message id')
+
     model_id = data['model']
     if model_id not in models:
         raise Exception('Model not found')
@@ -327,6 +331,9 @@ async def chat_completed(request: Request, form_data: dict, user: Any):
     except Exception as e:
         raise Exception(f'Error: {e}')
 
+    if not data.get('id'):
+        raise Exception('Missing message id')
+
     metadata = {
         'chat_id': data['chat_id'],
         'message_id': data['id'],
diff --git a/src/lib/apis/index.ts b/src/lib/apis/index.ts
index c46c86b80..fea2d3899 100644
--- a/src/lib/apis/index.ts
+++ b/src/lib/apis/index.ts
@@ -161,9 +161,12 @@ export const getModels = async (
 
 type ChatCompletedForm = {
 	model: string;
-	messages: string[];
+	messages: Record<string, unknown>[];
 	chat_id: string;
-	session_id: string;
+	session_id: string | undefined;
+	id: string;
+	filter_ids?: string[];
+	model_item?: unknown;
 };
 
 export const chatCompleted = async (token: string, body: ChatCompletedForm) => {
diff --git a/src/lib/components/chat/Chat.svelte b/src/lib/components/chat/Chat.svelte
index c82bb55fd..c3864bc74 100644
--- a/src/lib/components/chat/Chat.svelte
+++ b/src/lib/components/chat/Chat.svelte
@@ -1358,6 +1358,11 @@
 	};
 
 	const chatCompletedHandler = async (_chatId, modelId, responseMessageId, messages) => {
+		if (!responseMessageId) {
+			console.error('chatCompleted: missing message id', { chatId: _chatId, modelId, messageCount: messages?.length ?? 0 });
+			return;
+		}
+
 		const res = await chatCompleted(localStorage.token, {
 			model: modelId,
 			messages: messages.map((m) => ({