diff --git a/ddpui/utils/singletaskprogress.py b/ddpui/utils/singletaskprogress.py
index 50b8b58c0..5db5a1015 100644
--- a/ddpui/utils/singletaskprogress.py
+++ b/ddpui/utils/singletaskprogress.py
@@ -19,7 +19,10 @@ def __init__(self, task_key: str, expire_in_seconds: int) -> None:
 
     def get(self) -> list:
         """get the list of progress"""
-        return json.loads(self.redis.get(self.task_key_))
+        result = self.redis.get(self.task_key_)
+        if result is None:
+            return []
+        return json.loads(result)
 
     def set(self, progress: list) -> None:
         """set the list of progress"""