diff --git a/include/cos_defines.h b/include/cos_defines.h
index d29fdb8..5871d91 100644
--- a/include/cos_defines.h
+++ b/include/cos_defines.h
@@ -11,7 +11,7 @@
 
 namespace qcloud_cos {
 
-#define COS_CPP_SDK_VERSON "v5.5.10"
+#define COS_CPP_SDK_VERSON "v5.5.11"
 
 /// 路径分隔符
 const std::string kPathDelimiter = "/";
diff --git a/src/cos_sys_config.cpp b/src/cos_sys_config.cpp
index c81ba0a..5d2bec5 100644
--- a/src/cos_sys_config.cpp
+++ b/src/cos_sys_config.cpp
@@ -57,7 +57,7 @@ unsigned CosSysConfig::m_dns_cache_expire_seconds = 600;
 // dns cache大小
 unsigned CosSysConfig::m_dns_cache_size = 1000;
 
-bool CosSysConfig::m_retry_change_domain = true;
+bool CosSysConfig::m_retry_change_domain = false;
 
 std::mutex m_intranet_addr_lock;
 std::mutex m_dest_domain_lock;
diff --git a/src/op/object_op.cpp b/src/op/object_op.cpp
index 40b61d6..30271bd 100644
--- a/src/op/object_op.cpp
+++ b/src/op/object_op.cpp
@@ -1,4 +1,4 @@
-// Copyright (c) 2017, Tencent Inc.
+// Copyright (c) 2017, Tencent Inc.
 // All rights reserved.
 //
 // Author: sevenyou <sevenyou@tencent.com>
@@ -337,7 +337,11 @@ CosResult ObjectOp::HeadObject(const HeadObjectReq& req, HeadObjectResp* resp, b
   std::string host = CosSysConfig::GetHost(GetAppId(), m_config->GetRegion(),
                                            req.GetBucketName(),change_backup_domain);
   std::string path = req.GetPath();
-  return NormalAction(host, path, req, "", false, resp);
+  CosResult result = NormalAction(host, path, req, "", false, resp);
+  if (result.GetHttpStatus() == 404){
+    result.SetErrorCode("NoSuchKey");
+  }
+  return result;
 }
 
 CosResult ObjectOp::GetObject(const GetObjectByStreamReq& req,
@@ -1781,6 +1785,9 @@ void ObjectOp::FillCopyTask(const std::string& upload_id,
 }
 
 std::string ObjectOp::GeneratePresignedUrl(const GeneratePresignedUrlReq& req) {
+  if (req.GetObjectName().empty()) {
+    return "ObjectName does not support empty, please check!";
+  }
   std::string auth_str = "";
 
   std::string host;