diff --git a/api/core/rag/datasource/retrieval_service.py b/api/core/rag/datasource/retrieval_service.py
index 0c1158a658a..a4ac63004c1 100644
--- a/api/core/rag/datasource/retrieval_service.py
+++ b/api/core/rag/datasource/retrieval_service.py
@@ -1,4 +1,5 @@
 import concurrent.futures
+import logging
 from concurrent.futures import ThreadPoolExecutor
 from typing import Any
 
@@ -36,6 +37,8 @@ default_retrieval_model = {
     "score_threshold_enabled": False,
 }
 
+logger = logging.getLogger(__name__)
+
 
 class RetrievalService:
     # Cache precompiled regular expressions to avoid repeated compilation
@@ -108,7 +111,7 @@ class RetrievalService:
 
             if futures:
                 for future in concurrent.futures.as_completed(futures, timeout=3600):
-                    if future.exception():
+                    if exceptions:
                         for f in futures:
                             f.cancel()
                         break
@@ -215,6 +218,7 @@ class RetrievalService:
                 )
                 all_documents.extend(documents)
             except Exception as e:
+                logger.error(e, exc_info=True)
                 exceptions.append(str(e))
 
     @classmethod
@@ -308,6 +312,7 @@ class RetrievalService:
                     else:
                         all_documents.extend(documents)
             except Exception as e:
+                logger.error(e, exc_info=True)
                 exceptions.append(str(e))
 
     @classmethod
@@ -356,6 +361,7 @@ class RetrievalService:
                     else:
                         all_documents.extend(documents)
             except Exception as e:
+                logger.error(e, exc_info=True)
                 exceptions.append(str(e))
 
     @staticmethod
diff --git a/api/core/rag/retrieval/dataset_retrieval.py b/api/core/rag/retrieval/dataset_retrieval.py
index 1880a1b8b70..b32e3e8829d 100644
--- a/api/core/rag/retrieval/dataset_retrieval.py
+++ b/api/core/rag/retrieval/dataset_retrieval.py
@@ -569,10 +569,14 @@ class DatasetRetrieval:
                     all_threads.append(attachment_thread)
                     attachment_thread.start()
 
-            for thread in all_threads:
-                thread.join(timeout=300)
+            # Poll threads with short timeout to detect errors quickly (fail-fast)
+            while any(t.is_alive() for t in all_threads):
+                for thread in all_threads:
+                    thread.join(timeout=0.1)
+                    if thread_exceptions:
+                        cancel_event.set()
+                        break
                 if thread_exceptions:
-                    cancel_event.set()
                     break
 
             if thread_exceptions:
@@ -1454,9 +1458,13 @@ class DatasetRetrieval:
                     )
                     threads.append(retrieval_thread)
                     retrieval_thread.start()
-                for thread in threads:
-                    thread.join(timeout=300)
-                    # Check for cancellation signal between threads
+
+                # Poll threads with short timeout to respond quickly to cancellation
+                while any(t.is_alive() for t in threads):
+                    for thread in threads:
+                        thread.join(timeout=0.1)
+                        if cancel_event and cancel_event.is_set():
+                            break
                     if cancel_event and cancel_event.is_set():
                         break