diff --git a/dbms/src/Storages/DeltaMerge/File/DMFileWithVectorIndexBlockInputStream.cpp b/dbms/src/Storages/DeltaMerge/File/DMFileWithVectorIndexBlockInputStream.cpp
index 562b3756725..d0864ccb302 100644
--- a/dbms/src/Storages/DeltaMerge/File/DMFileWithVectorIndexBlockInputStream.cpp
+++ b/dbms/src/Storages/DeltaMerge/File/DMFileWithVectorIndexBlockInputStream.cpp
@@ -353,6 +353,7 @@ void DMFileWithVectorIndexBlockInputStream::loadVectorSearchResult()
 
     auto perf_begin = PerfContext::vector_search;
 
+    RUNTIME_CHECK(valid_rows.size() >= dmfile->getRows(), valid_rows.size(), dmfile->getRows());
     auto results_rowid = vec_index->search(ann_query_info, valid_rows);
 
     auto discarded_nodes = PerfContext::vector_search.discarded_nodes - perf_begin.discarded_nodes;
diff --git a/dbms/src/Storages/DeltaMerge/File/VectorColumnFromIndexReader.cpp b/dbms/src/Storages/DeltaMerge/File/VectorColumnFromIndexReader.cpp
index ffb559bd33d..25d4842e75a 100644
--- a/dbms/src/Storages/DeltaMerge/File/VectorColumnFromIndexReader.cpp
+++ b/dbms/src/Storages/DeltaMerge/File/VectorColumnFromIndexReader.cpp
@@ -39,6 +39,8 @@ MutableColumnPtr VectorColumnFromIndexReader::calcResultsByPack(
 
     // results must be in ascending order.
     std::sort(results.begin(), results.end());
+    // results must not contain duplicates. Usually there should be no duplicates.
+    results.erase(std::unique(results.begin(), results.end()), results.end());
 
     std::vector<UInt32> offsets_in_pack;
     size_t results_it = 0;
diff --git a/dbms/src/Storages/DeltaMerge/Index/VectorIndexHNSW/Index.cpp b/dbms/src/Storages/DeltaMerge/Index/VectorIndexHNSW/Index.cpp
index 5a983824f18..b499fed5ec3 100644
--- a/dbms/src/Storages/DeltaMerge/Index/VectorIndexHNSW/Index.cpp
+++ b/dbms/src/Storages/DeltaMerge/Index/VectorIndexHNSW/Index.cpp
@@ -155,13 +155,24 @@ std::vector<VectorIndexBuilder::Key> VectorIndexHNSWViewer::search(
 
     std::atomic<size_t> visited_nodes = 0;
     std::atomic<size_t> discarded_nodes = 0;
+    std::atomic<bool> has_exception_in_search = false;
 
     auto predicate = [&](typename USearchImplType::member_cref_t const & member) {
-        // Note: We don't increase the thread_local perf, to be compatible with future multi-thread change.
-        visited_nodes++;
-        if (!valid_rows[member.key])
-            discarded_nodes++;
-        return valid_rows[member.key];
+        // Must catch exceptions in the predicate, because search runs on other threads.
+        try
+        {
+            // Note: We don't increase the thread_local perf, because search runs on other threads.
+            visited_nodes++;
+            if (!valid_rows[member.key])
+                discarded_nodes++;
+            return valid_rows[member.key];
+        }
+        catch (...)
+        {
+            tryLogCurrentException(__PRETTY_FUNCTION__);
+            has_exception_in_search = true;
+            return false;
+        }
     };
 
     // TODO: Support efSearch.
@@ -169,6 +180,10 @@ std::vector<VectorIndexBuilder::Key> VectorIndexHNSWViewer::search(
         reinterpret_cast<const Float32 *>(query_info->ref_vec_f32().data() + sizeof(UInt32)),
         query_info->top_k(),
         predicate);
+
+    if (has_exception_in_search)
+        throw Exception(ErrorCodes::INCORRECT_QUERY, "Exception happened occurred during search");
+
     std::vector<Key> keys(result.size());
     result.dump_to(keys.data());
 
diff --git a/dbms/src/Storages/DeltaMerge/tests/gtest_dm_vector_index.cpp b/dbms/src/Storages/DeltaMerge/tests/gtest_dm_vector_index.cpp
index 4ebfa77ed30..67c6c2dce42 100644
--- a/dbms/src/Storages/DeltaMerge/tests/gtest_dm_vector_index.cpp
+++ b/dbms/src/Storages/DeltaMerge/tests/gtest_dm_vector_index.cpp
@@ -498,6 +498,73 @@ try
 }
 CATCH
 
+TEST_P(VectorIndexDMFileTest, OnePackWithDuplicateVectors)
+try
+{
+    auto cols = DMTestEnv::getDefaultColumns(DMTestEnv::PkType::HiddenTiDBRowID, /*add_nullable*/ true);
+    auto vec_cd = ColumnDefine(vec_column_id, vec_column_name, tests::typeFromString("Array(Float32)"));
+    vec_cd.vector_index = std::make_shared<TiDB::VectorIndexDefinition>(TiDB::VectorIndexDefinition{
+        .kind = tipb::VectorIndexKind::HNSW,
+        .dimension = 3,
+        .distance_metric = tipb::VectorDistanceMetric::L2,
+    });
+    cols->emplace_back(vec_cd);
+
+    ColumnDefines read_cols = *cols;
+    if (test_only_vec_column)
+        read_cols = {vec_cd};
+
+    // Prepare DMFile
+    {
+        Block block = DMTestEnv::prepareSimpleWriteBlockWithNullable(0, 5);
+        block.insert(createVecFloat32Column<Array>(
+            {//
+             {1.0, 2.0, 3.0},
+             {1.0, 2.0, 3.0},
+             {0.0, 0.0, 0.0},
+             {1.0, 2.0, 3.0},
+             {1.0, 2.0, 3.5}},
+            vec_cd.name,
+            vec_cd.id));
+        auto stream = std::make_shared<DMFileBlockOutputStream>(dbContext(), dm_file, *cols);
+        stream->writePrefix();
+        stream->write(block, DMFileBlockOutputStream::BlockProperty{0, 0, 0, 0});
+        stream->writeSuffix();
+    }
+
+    dm_file = restoreDMFile();
+
+    {
+        auto ann_query_info = std::make_shared<tipb::ANNQueryInfo>();
+        ann_query_info->set_column_id(vec_cd.id);
+        ann_query_info->set_distance_metric(tipb::VectorDistanceMetric::L2);
+        ann_query_info->set_top_k(4);
+        ann_query_info->set_ref_vec_f32(encodeVectorFloat32({1.0, 2.0, 3.5}));
+
+        DMFileBlockInputStreamBuilder builder(dbContext());
+        auto stream = builder.setRSOperator(wrapWithANNQueryInfo(nullptr, ann_query_info))
+                          .setBitmapFilter(BitmapFilterView(std::make_shared<BitmapFilter>(5, true), 0, 5))
+                          .build2(
+                              dm_file,
+                              read_cols,
+                              RowKeyRanges{RowKeyRange::newAll(false, 1)},
+                              std::make_shared<ScanContext>());
+
+        ASSERT_INPUTSTREAM_COLS_UR(
+            stream,
+            createColumnNames(),
+            createColumnData({
+                createColumn<Int64>({0, 1, 3, 4}),
+                createVecFloat32Column<Array>({//
+                                               {1.0, 2.0, 3.0},
+                                               {1.0, 2.0, 3.0},
+                                               {1.0, 2.0, 3.0},
+                                               {1.0, 2.0, 3.5}}),
+            }));
+    }
+}
+CATCH
+
 TEST_P(VectorIndexDMFileTest, MultiPacks)
 try
 {