diff --git a/agent/tools/retrieval.py b/agent/tools/retrieval.py
index c3a01e517..001b8a49e 100644
--- a/agent/tools/retrieval.py
+++ b/agent/tools/retrieval.py
@@ -167,7 +167,7 @@ class Retrieval(ToolBase, ABC):
                     flt["value"] = "".join(out_parts)
                 doc_ids.extend(meta_filter(metas, filters, self._param.meta_data_filter.get("logic", "and")))
                 if not doc_ids:
-                    doc_ids = None
+                    doc_ids = ["-999"]
 
         if self._param.cross_languages:
             query = cross_languages(kbs[0].tenant_id, None, query, self._param.cross_languages)
diff --git a/api/apps/chunk_app.py b/api/apps/chunk_app.py
index e121bcba7..f48276d0a 100644
--- a/api/apps/chunk_app.py
+++ b/api/apps/chunk_app.py
@@ -312,7 +312,7 @@ async def retrieval_test():
         elif meta_data_filter.get("method") == "manual":
             doc_ids.extend(meta_filter(metas, meta_data_filter["manual"], meta_data_filter.get("logic", "and")))
             if not doc_ids:
-                doc_ids = None
+                doc_ids = ["-999"]
 
     try:
         tenants = UserTenantService.query(user_id=current_user.id)
diff --git a/api/apps/sdk/doc.py b/api/apps/sdk/doc.py
index 84300ac3c..f507c3abf 100644
--- a/api/apps/sdk/doc.py
+++ b/api/apps/sdk/doc.py
@@ -1445,6 +1445,8 @@ async def retrieval_test(tenant_id):
         metadata_condition = req.get("metadata_condition", {}) or {}
         metas = DocumentService.get_meta_by_kbs(kb_ids)
         doc_ids = meta_filter(metas, convert_conditions(metadata_condition), metadata_condition.get("logic", "and"))
+        if not doc_ids:
+            doc_ids = ["-999"]
     similarity_threshold = float(req.get("similarity_threshold", 0.2))
     vector_similarity_weight = float(req.get("vector_similarity_weight", 0.3))
     top = int(req.get("top_k", 1024))
diff --git a/api/apps/sdk/session.py b/api/apps/sdk/session.py
index 533375622..c43292fbb 100644
--- a/api/apps/sdk/session.py
+++ b/api/apps/sdk/session.py
@@ -982,7 +982,7 @@ async def retrieval_test_embedded():
         elif meta_data_filter.get("method") == "manual":
             doc_ids.extend(meta_filter(metas, meta_data_filter["manual"], meta_data_filter.get("logic", "and")))
             if not doc_ids:
-                doc_ids = None
+                doc_ids = ["-999"]
 
     try:
         tenants = UserTenantService.query(user_id=tenant_id)
diff --git a/api/db/services/dialog_service.py b/api/db/services/dialog_service.py
index db878574d..2bbe916de 100644
--- a/api/db/services/dialog_service.py
+++ b/api/db/services/dialog_service.py
@@ -417,7 +417,7 @@ def chat(dialog, messages, stream=True, **kwargs):
         elif dialog.meta_data_filter.get("method") == "manual":
             attachments.extend(meta_filter(metas, dialog.meta_data_filter["manual"], dialog.meta_data_filter.get("logic", "and")))
             if not attachments:
-                attachments = None
+                attachments = ["-999"]
 
     if prompt_config.get("keyword", False):
         questions[-1] += keyword_extraction(chat_mdl, questions[-1])
@@ -788,7 +788,7 @@ def ask(question, kb_ids, tenant_id, chat_llm_name=None, search_config={}):
         elif meta_data_filter.get("method") == "manual":
             doc_ids.extend(meta_filter(metas, meta_data_filter["manual"], meta_data_filter.get("logic", "and")))
             if not doc_ids:
-                doc_ids = None
+                doc_ids = ["-999"]
 
     kbinfos = retriever.retrieval(
         question=question,
@@ -863,7 +863,7 @@ def gen_mindmap(question, kb_ids, tenant_id, search_config={}):
         elif meta_data_filter.get("method") == "manual":
             doc_ids.extend(meta_filter(metas, meta_data_filter["manual"], meta_data_filter.get("logic", "and")))
             if not doc_ids:
-                doc_ids = None
+                doc_ids = ["-999"]
 
     ranks = settings.retriever.retrieval(
         question=question,