diff --git a/frontend/components/KnowledgeBase.tsx b/frontend/components/KnowledgeBase.tsx
index b6311a4..cbbcb29 100644
--- a/frontend/components/KnowledgeBase.tsx
+++ b/frontend/components/KnowledgeBase.tsx
@@ -128,6 +128,11 @@ export const KnowledgeBase: React.FC = () => {
                     }
                 } catch (err) {
                     console.error('Failed to poll job:', err);
+                    // Stop polling on error (e.g. 404 job not found)
+                    setActiveJob(null);
+                    if (pollRef.current) clearInterval(pollRef.current);
+                    pollRef.current = null;
+                    loadKbDetail(selectedKb.id);
                 }
             }, 3000);
         }