diff --git a/api/core/workflow/nodes/answer/answer_stream_generate_router.py b/api/core/workflow/nodes/answer/answer_stream_generate_router.py
index 1b948bf59203b7..7d652d39f70ef4 100644
--- a/api/core/workflow/nodes/answer/answer_stream_generate_router.py
+++ b/api/core/workflow/nodes/answer/answer_stream_generate_router.py
@@ -147,6 +147,8 @@ def _recursive_fetch_answer_dependencies(
         reverse_edges = reverse_edge_mapping.get(current_node_id, [])
         for edge in reverse_edges:
             source_node_id = edge.source_node_id
+            if source_node_id not in node_id_config_mapping:
+                continue
             source_node_type = node_id_config_mapping[source_node_id].get("data", {}).get("type")
             source_node_data = node_id_config_mapping[source_node_id].get("data", {})
             if (
diff --git a/api/core/workflow/nodes/end/end_stream_generate_router.py b/api/core/workflow/nodes/end/end_stream_generate_router.py
index ea8b6b50420c99..0db1ba9f09d36e 100644
--- a/api/core/workflow/nodes/end/end_stream_generate_router.py
+++ b/api/core/workflow/nodes/end/end_stream_generate_router.py
@@ -135,6 +135,8 @@ def _recursive_fetch_end_dependencies(
         reverse_edges = reverse_edge_mapping.get(current_node_id, [])
         for edge in reverse_edges:
             source_node_id = edge.source_node_id
+            if source_node_id not in node_id_config_mapping:
+                continue
             source_node_type = node_id_config_mapping[source_node_id].get("data", {}).get("type")
             if source_node_type in {
                 NodeType.IF_ELSE.value,