diff --git a/cpp/CHANGELOG.md b/cpp/CHANGELOG.md
index dab772d02f032a06a986efff37f68e60317b5bc5..96745a8cdff0c54bc07ea79af096cce85a2c5ef9 100644
--- a/cpp/CHANGELOG.md
+++ b/cpp/CHANGELOG.md
@@ -107,6 +107,7 @@ Please mark all change in change log and use the ticket from JIRA.
 - MS-525 - Disable parallel reduce in SearchTask
 - MS-527 - Update scheduler_test and enable it
 - MS-528 - Hide some config used future
+- MS-530 - Add unittest for SearchTask->Load
 
 ## New Feature
 - MS-343 - Implement ResourceMgr
diff --git a/cpp/src/scheduler/task/SearchTask.cpp b/cpp/src/scheduler/task/SearchTask.cpp
index 47d553292120ad77acb7cecd11757006a80f49ee..8d76075014984902992cddfa5663ecfdda966be4 100644
--- a/cpp/src/scheduler/task/SearchTask.cpp
+++ b/cpp/src/scheduler/task/SearchTask.cpp
@@ -96,33 +96,31 @@ XSearchTask::XSearchTask(TableFileSchemaPtr file)
 void
 XSearchTask::Load(LoadType type, uint8_t device_id) {
     server::TimeRecorder rc("");
+    Status stat = Status::OK();
+    std::string error_msg;
 
     try {
         if (type == LoadType::DISK2CPU) {
-            auto stat = index_engine_->Load();
-            if(!stat.ok()) {
-                //typical error: file not available
-                ENGINE_LOG_ERROR << "Failed to load index file: file not available";
-
-                for(auto& context : search_contexts_) {
-                    context->IndexSearchDone(file_->id_);//mark as done avoid dead lock, even failed
-                }
-
-                return;
-            }
+            stat = index_engine_->Load();
         } else if (type == LoadType::CPU2GPU) {
-            index_engine_->CopyToGpu(device_id);
+            stat = index_engine_->CopyToGpu(device_id);
         } else if (type == LoadType::GPU2CPU) {
-            index_engine_->CopyToCpu();
+            stat = index_engine_->CopyToCpu();
         } else {
-            // TODO: exception
-            std::string msg = "Wrong load type";
-            ENGINE_LOG_ERROR << msg;
+            error_msg = "Wrong load type";
+            stat = Status(SERVER_UNEXPECTED_ERROR, error_msg);
         }
     } catch (std::exception &ex) {
         //typical error: out of disk space or permition denied
-        std::string msg = "Failed to load index file: " + std::string(ex.what());
-        ENGINE_LOG_ERROR << msg;
+        error_msg = "Failed to load index file: " + std::string(ex.what());
+        stat = Status(SERVER_UNEXPECTED_ERROR, error_msg);
+    }
+
+    if (!stat.ok()) {
+        if (error_msg.empty())
+            error_msg = std::string("Failed to load index file: file not available");
+        //typical error: file not available
+        ENGINE_LOG_ERROR << error_msg;
 
         for (auto &context : search_contexts_) {
             context->IndexSearchDone(file_->id_);//mark as done avoid dead lock, even failed
@@ -241,7 +239,7 @@ Status XSearchTask::ClusterResult(const std::vector<long> &output_ids,
 //    if (NeedParallelReduce(nq, topk)) {
 //        ParallelReduce(reduce_worker, nq);
 //    } else {
-        reduce_worker(0, nq);
+    reduce_worker(0, nq);
 //    }
 
     return Status::OK();
@@ -346,7 +344,7 @@ Status XSearchTask::TopkResult(SearchContext::ResultSet &result_src,
 //    if (NeedParallelReduce(result_src.size(), topk)) {
 //        ParallelReduce(ReduceWorker, result_src.size());
 //    } else {
-        ReduceWorker(0, result_src.size());
+    ReduceWorker(0, result_src.size());
 //    }
 
     return Status::OK();
diff --git a/cpp/unittest/scheduler/normal_test.cpp b/cpp/unittest/scheduler/normal_test.cpp
index bb438ab9148710a6a9fecd82172b401a7e7347d7..c679a356bd8d5435dc623a3c2ca6df181eb6539d 100644
--- a/cpp/unittest/scheduler/normal_test.cpp
+++ b/cpp/unittest/scheduler/normal_test.cpp
@@ -11,7 +11,7 @@
 using namespace zilliz::milvus::engine;
 
 
-TEST(normal_test, DISABLED_inst_test) {
+TEST(normal_test, inst_test) {
     // ResourceMgr only compose resources, provide unified event
     auto res_mgr = ResMgrInst::GetInstance();
 
diff --git a/cpp/unittest/scheduler/task_test.cpp b/cpp/unittest/scheduler/task_test.cpp
index b3c29af367c76e0fb775e4f890616f693be30f5f..f42006fc5269a839458a62df2ccdc6b2426b5674 100644
--- a/cpp/unittest/scheduler/task_test.cpp
+++ b/cpp/unittest/scheduler/task_test.cpp
@@ -1,4 +1,23 @@
-//
-// Created by wxyu on 19-9-9.
-//
+/*******************************************************************************
+ * Copyright 上海赜睿信息科技有限公司(Zilliz) - All Rights Reserved
+ * Unauthorized copying of this file, via any medium is strictly prohibited.
+ * Proprietary and confidential.
+ ******************************************************************************/
 
+#include "scheduler/task/SearchTask.h"
+#include <gtest/gtest.h>
+
+
+namespace zilliz {
+namespace milvus {
+namespace engine {
+
+
+TEST(TaskTest, invalid_index) {
+    auto search_task = std::make_shared<XSearchTask>(nullptr);
+    search_task->Load(LoadType::TEST, 10);
+}
+
+}
+}
+}