diff --git a/backend/open_webui/main.py b/backend/open_webui/main.py
index 96a85be50e..63f5fc6ccb 100644
--- a/backend/open_webui/main.py
+++ b/backend/open_webui/main.py
@@ -1560,9 +1560,10 @@ async def chat_completion(
                             for mid, message in turn['messages'].items()
                         }
                         await event_emitter({'type': 'chat:messages', 'data': turn})
-                        await emit_chat_list_event({**metadata, 'message_id': user_message['id']}, chat_id)
+                        user_message_id = user_message.get('id')
+                        await emit_chat_list_event({**metadata, 'message_id': user_message_id}, chat_id)
                         for message_id, message in turn['messages'].items():
-                            if message_id != user_message['id'] and message.get('parentId') != user_message['id']:
+                            if message_id != user_message_id and message.get('parentId') != user_message_id:
                                 continue
                             await publish_event(
                                 request,
@@ -1571,7 +1572,10 @@ async def chat_completion(
                                 subject_id=message_id,
                                 data={'chat_id': chat_id, 'role': message['role'], 'model': message.get('model')},
                             )
-                        if not getattr(request.state, 'internal', False):
+                        if user_message_id and not (
+                            getattr(request.state, 'internal', False)
+                            or (user_message.get('meta') or {}).get('internal')
+                        ):
                             try:
                                 from open_webui.utils.timers import cancel_timers_for_chat
 
diff --git a/backend/open_webui/models/chats.py b/backend/open_webui/models/chats.py
index cb2eac689f..cfc59bc0e7 100644
--- a/backend/open_webui/models/chats.py
+++ b/backend/open_webui/models/chats.py
@@ -1196,35 +1196,52 @@ class ChatTable:
                 raise HTTPException(404, 'Chat not found.')
             history = (chat.chat or {}).get('history') or {'messages': {}, 'currentId': None}
             messages = history.get('messages') or {}
-            ids = [user_message.get('id'), *[entry.get('message_id') for entry in message_ids]]
-            if (
-                not all(isinstance(mid, str) and mid for mid in ids)
-                or len(set(ids)) != len(ids)
-                or any(mid in messages for mid in ids[1:])
-            ):
+            user_message_id = user_message.get('id')
+            assistant_ids = [entry.get('message_id') for entry in message_ids]
+            ids = [user_message_id, *assistant_ids] if user_message else assistant_ids
+            if not all(isinstance(mid, str) and mid for mid in ids) or len(set(ids)) != len(ids):
                 raise HTTPException(409, 'Message already exists or has an invalid ID.')
-            existing = messages.get(ids[0])
-            if existing and (existing.get('role') != 'user' or (existing.get('user_id') or chat.user_id) != user.id):
-                raise HTTPException(403, 'You can only regenerate your own messages.')
-            parent_id = existing.get('parentId') if existing else user_message.get('parentId')
-            if parent_id is not None and parent_id not in messages:
-                raise HTTPException(409, 'Parent message no longer exists.')
-            message = existing or (
-                dict(user_message)
-                if chat.user_id == user.id
-                else {key: user_message[key] for key in ('content', 'files', 'models') if key in user_message}
-            )
-            if not existing:
-                message.update(
-                    id=ids[0],
-                    parentId=parent_id,
-                    role='user',
-                    childrenIds=[],
-                    timestamp=int(time.time()),
-                    user_id=user.id,
-                    user={'id': user.id, 'name': user.name},
+            # An empty reply may be prepared before the request.
+            for mid in assistant_ids:
+                existing_reply = messages.get(mid)
+                if existing_reply and (
+                    existing_reply.get('role') != 'assistant'
+                    or existing_reply.get('done')
+                    or existing_reply.get('content')
+                    or existing_reply.get('output')
+                    or (existing_reply.get('user_id') or chat.user_id) != user.id
+                    or (user_message and existing_reply.get('parentId') != user_message_id)
+                ):
+                    raise HTTPException(409, 'Message already exists or has an invalid ID.')
+            turn = {}
+            parent_id = None
+            if user_message:
+                existing = messages.get(user_message_id)
+                if existing and (
+                    existing.get('role') != 'user' or (existing.get('user_id') or chat.user_id) != user.id
+                ):
+                    raise HTTPException(403, 'You can only regenerate your own messages.')
+                parent_id = existing.get('parentId') if existing else user_message.get('parentId')
+                if parent_id is not None and parent_id not in messages:
+                    raise HTTPException(409, 'Parent message no longer exists.')
+                message = existing or (
+                    dict(user_message)
+                    if chat.user_id == user.id
+                    else {key: user_message[key] for key in ('content', 'files', 'models') if key in user_message}
+                )
+                if not existing:
+                    message.update(
+                        id=user_message_id,
+                        parentId=parent_id,
+                        role='user',
+                        childrenIds=[],
+                        timestamp=int(time.time()),
+                        user_id=user.id,
+                        user={'id': user.id, 'name': user.name},
+                    )
+                turn[user_message_id] = self.upsert_message_to_history(
+                    history, user_message_id, self._clean_null_bytes(message)
                 )
-            turn = {ids[0]: self.upsert_message_to_history(history, ids[0], self._clean_null_bytes(message))}
             for entry in message_ids:
                 mid = entry['message_id']
                 turn[mid] = self.upsert_message_to_history(
@@ -1232,7 +1249,7 @@ class ChatTable:
                     mid,
                     {
                         'id': mid,
-                        'parentId': ids[0],
+                        'parentId': user_message_id,
                         'childrenIds': [],
                         'role': 'assistant',
                         'content': '',