diff --git a/backend/open_webui/routers/chats.py b/backend/open_webui/routers/chats.py
index 256455fffb..c618334783 100644
--- a/backend/open_webui/routers/chats.py
+++ b/backend/open_webui/routers/chats.py
@@ -30,6 +30,7 @@ from open_webui.models.folders import Folders
 from open_webui.models.shared_chats import SharedChatResponse, SharedChats
 from open_webui.models.tags import TagModel, Tags
 from open_webui.socket.main import get_event_emitter
+from open_webui.tasks import stop_item_tasks
 from open_webui.utils.access_control import filter_allowed_access_grants, has_permission
 from open_webui.utils.auth import get_admin_user, get_verified_user
 from open_webui.utils.middleware import serialize_output
@@ -1116,6 +1117,10 @@ async def delete_chat_by_id(
     user=Depends(get_verified_user),
     db: AsyncSession = Depends(get_async_session),
 ):
+    # Cancel any in-flight LLM tasks (streaming, title/tags generation)
+    # before deleting the chat to prevent orphaned requests.
+    await stop_item_tasks(request.app.state.redis, id)
+
     if user.role == 'admin':
         chat = await Chats.get_chat_by_id(id, db=db)
         if not chat:
@@ -1305,13 +1310,20 @@ async def clone_shared_chat_by_id(
 
 
 @router.post('/{id}/archive', response_model=ChatResponse | None)
-async def archive_chat_by_id(id: str, user=Depends(get_verified_user), db: AsyncSession = Depends(get_async_session)):
+async def archive_chat_by_id(
+    request: Request,
+    id: str,
+    user=Depends(get_verified_user),
+    db: AsyncSession = Depends(get_async_session),
+):
     chat = await Chats.get_chat_by_id_and_user_id(id, user.id, db=db)
     if chat:
         chat = await Chats.toggle_chat_archive_by_id(id, db=db)
 
         tag_ids = chat.meta.get('tags', [])
         if chat.archived:
+            # Cancel any in-flight LLM tasks before archiving
+            await stop_item_tasks(request.app.state.redis, id)
             # Archived chats are excluded from count — clean up orphans
             await Chats.delete_orphan_tags_for_user(tag_ids, user.id, db=db)
         else:
diff --git a/backend/open_webui/utils/middleware.py b/backend/open_webui/utils/middleware.py
index a91dd31bd6..fa6e1bddb3 100644
--- a/backend/open_webui/utils/middleware.py
+++ b/backend/open_webui/utils/middleware.py
@@ -3070,7 +3070,10 @@ async def background_tasks_handler(ctx):
         and not metadata.get('chat_id', '').startswith('channel:')
     ):
         messages_map = await Chats.get_messages_map_by_chat_id(metadata['chat_id'])
-        message = messages_map.get(metadata['message_id']) if messages_map else None
+        if not messages_map:
+            # Chat was deleted while the response was streaming — skip background tasks
+            return
+        message = messages_map.get(metadata['message_id'])
 
         message_list = get_message_list(messages_map, metadata['message_id'])