diff --git a/api/db/services/document_service.py b/api/db/services/document_service.py
index 4e94f928..4c59271e 100644
--- a/api/db/services/document_service.py
+++ b/api/db/services/document_service.py
@@ -504,6 +504,9 @@ def doc_upload_and_parse(conversation_id, file_objs, user_id):
     assert e, "Conversation not found!"
 
     e, dia = DialogService.get_by_id(conv.dialog_id)
+    if not dia.kb_ids:
+        raise LookupError("No knowledge base associated with this conversation. "
+                          "Please add a knowledge base before uploading documents")
     kb_id = dia.kb_ids[0]
     e, kb = KnowledgebaseService.get_by_id(kb_id)
     if not e: