diff --git a/coscmd/cos_client.py b/coscmd/cos_client.py
index f117697..5484bfb 100644
--- a/coscmd/cos_client.py
+++ b/coscmd/cos_client.py
@@ -1493,7 +1493,7 @@ def download_file(self, cos_path, local_path, _http_headers='{}', **kwargs):
                 os.makedirs(dir_path, 0o755)
             except Exception as e:
                 pass
-        if kwargs["versionId"] != "":
+        if ("versionId" in kwargs) and (kwargs["versionId"] != ""):
             _http_headers["VersionId"] = kwargs["versionId"]
         if file_size <= self._multidownload_threshold:
             try:
diff --git a/coscmd/cos_global.py b/coscmd/cos_global.py
index 4f0ed05..9cec380 100644
--- a/coscmd/cos_global.py
+++ b/coscmd/cos_global.py
@@ -1 +1 @@
-Version = "1.8.6.33"
+Version = "1.8.6.34"