diff --git a/api/core/rag/retrieval/dataset_retrieval.py b/api/core/rag/retrieval/dataset_retrieval.py
index 38c0b540d5..3fca48be22 100644
--- a/api/core/rag/retrieval/dataset_retrieval.py
+++ b/api/core/rag/retrieval/dataset_retrieval.py
@@ -1010,6 +1010,9 @@ class DatasetRetrieval:
     def _process_metadata_filter_func(
         self, sequence: int, condition: str, metadata_name: str, value: Optional[Any], filters: list
     ):
+        if value is None:
+            return
+
         key = f"{metadata_name}_{sequence}"
         key_value = f"{metadata_name}_{sequence}_value"
         match condition:
diff --git a/api/core/workflow/nodes/knowledge_retrieval/knowledge_retrieval_node.py b/api/core/workflow/nodes/knowledge_retrieval/knowledge_retrieval_node.py
index 0b9e98f28a..b34d62d669 100644
--- a/api/core/workflow/nodes/knowledge_retrieval/knowledge_retrieval_node.py
+++ b/api/core/workflow/nodes/knowledge_retrieval/knowledge_retrieval_node.py
@@ -490,6 +490,9 @@ class KnowledgeRetrievalNode(LLMNode):
     def _process_metadata_filter_func(
         self, sequence: int, condition: str, metadata_name: str, value: Optional[Any], filters: list
     ):
+        if value is None:
+            return
+
         key = f"{metadata_name}_{sequence}"
         key_value = f"{metadata_name}_{sequence}_value"
         match condition: