diff --git a/ydb/pool.py b/ydb/pool.py
index 0fb3e86a..9b53d717 100644
--- a/ydb/pool.py
+++ b/ydb/pool.py
@@ -416,7 +416,8 @@ def _on_disconnected(self, connection):
         :return: None
         """
         connection.close()
-        self._discovery_thread.notify_disconnected()
+        if self._discovery_thread:
+            self._discovery_thread.notify_disconnected()
 
     def discovery_debug_details(self):
         """