diff --git a/rag/nlp/search.py b/rag/nlp/search.py
index 57b663400e..87c1c6682a 100644
--- a/rag/nlp/search.py
+++ b/rag/nlp/search.py
@@ -781,6 +781,13 @@ class Dealer:
         vector_size = 1024
         for id, cks in mom_chunks.items():
             chunk = self.dataStore.get(id, idx_nms[0], [ck["kb_id"] for ck in cks])
+            if chunk is None:
+                logging.warning(
+                    "Parent chunk '%s' not found in the index; falling back to %d child chunk(s).",
+                    id, len(cks),
+                )
+                chunks.extend(cks)
+                continue
             d = {
                 "chunk_id": id,
                 "content_ltks": " ".join([ck["content_ltks"] for ck in cks]),