diff --git a/HISTORY.md b/HISTORY.md
index 556b25782..ed7561af2 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -22,6 +22,7 @@
 
 ### Bug Fixes
 * Fail recovery and report once hitting a physical log record checksum mismatch, while reading MANIFEST. RocksDB should not continue processing the MANIFEST any further.
+* Fix a bug when index_type == kTwoLevelIndexSearch in PartitionedIndexBuilder to update FlushPolicy to point to internal key partitioner when it changes from user-key mode to internal-key mode in index partition.
 
 ## 6.11 (6/12/2020)
 ### Bug Fixes
diff --git a/db/db_test2.cc b/db/db_test2.cc
index a0fc938b0..fd2933b8c 100644
--- a/db/db_test2.cc
+++ b/db/db_test2.cc
@@ -144,6 +144,38 @@ INSTANTIATE_TEST_CASE_P(TestReadOnlyWithCompressedCache,
                         TestReadOnlyWithCompressedCache,
                         ::testing::Combine(::testing::Values(-1, 100),
                                            ::testing::Bool()));
+
+class PartitionedIndexTestListener : public EventListener {
+ public:
+  void OnFlushCompleted(DB* /*db*/, const FlushJobInfo& info) override {
+    ASSERT_GT(info.table_properties.index_partitions, 1);
+    ASSERT_EQ(info.table_properties.index_key_is_user_key, 0);
+  }
+};
+
+TEST_F(DBTest2, PartitionedIndexUserToInternalKey) {
+  BlockBasedTableOptions table_options;
+  Options options = CurrentOptions();
+  table_options.index_type = BlockBasedTableOptions::kTwoLevelIndexSearch;
+  PartitionedIndexTestListener* listener = new PartitionedIndexTestListener();
+  options.table_factory.reset(NewBlockBasedTableFactory(table_options));
+  options.listeners.emplace_back(listener);
+  std::vector<const Snapshot*> snapshots;
+  Reopen(options);
+  Random rnd(301);
+
+  for (int i = 0; i < 3000; i++) {
+    int j = i % 30;
+    std::string value = RandomString(&rnd, 10500);
+    ASSERT_OK(Put("keykey_" + std::to_string(j), value));
+    snapshots.push_back(db_->GetSnapshot());
+  }
+  Flush();
+  for (auto s : snapshots) {
+    db_->ReleaseSnapshot(s);
+  }
+}
+
 #endif  // ROCKSDB_LITE
 
 class PrefixFullBloomWithReverseComparator
diff --git a/table/block_based/index_builder.cc b/table/block_based/index_builder.cc
index 277bec61d..a052c65d6 100644
--- a/table/block_based/index_builder.cc
+++ b/table/block_based/index_builder.cc
@@ -112,6 +112,7 @@ void PartitionedIndexBuilder::MakeNewSubIndexBuilder() {
           ? sub_index_builder_->index_block_builder_
           : sub_index_builder_->index_block_builder_without_seq_));
   partition_cut_requested_ = false;
+  seperator_is_key_plus_seq_ = false;
 }
 
 void PartitionedIndexBuilder::RequestPartitionCut() {
@@ -129,9 +130,15 @@ void PartitionedIndexBuilder::AddIndexEntry(
     }
     sub_index_builder_->AddIndexEntry(last_key_in_current_block,
                                       first_key_in_next_block, block_handle);
-    if (sub_index_builder_->seperator_is_key_plus_seq_) {
-      // then we need to apply it to all sub-index builders
+    if (!seperator_is_key_plus_seq_ &&
+        sub_index_builder_->seperator_is_key_plus_seq_) {
+      // then we need to apply it to all sub-index builders and reset
+      // flush_policy to point to Block Builder of sub_index_builder_ that store
+      // internal keys.
       seperator_is_key_plus_seq_ = true;
+      flush_policy_.reset(FlushBlockBySizePolicyFactory::NewFlushBlockPolicy(
+          table_opt_.metadata_block_size, table_opt_.block_size_deviation,
+          sub_index_builder_->index_block_builder_));
     }
     sub_index_last_key_ = std::string(*last_key_in_current_block);
     entries_.push_back(
@@ -161,8 +168,14 @@ void PartitionedIndexBuilder::AddIndexEntry(
     sub_index_builder_->AddIndexEntry(last_key_in_current_block,
                                       first_key_in_next_block, block_handle);
     sub_index_last_key_ = std::string(*last_key_in_current_block);
-    if (sub_index_builder_->seperator_is_key_plus_seq_) {
-      // then we need to apply it to all sub-index builders
+    if (!seperator_is_key_plus_seq_ &&
+        sub_index_builder_->seperator_is_key_plus_seq_) {
+      // then we need to apply it to all sub-index builders and reset
+      // flush_policy to point to Block Builder of sub_index_builder_ that store
+      // internal keys.
+      flush_policy_.reset(FlushBlockBySizePolicyFactory::NewFlushBlockPolicy(
+          table_opt_.metadata_block_size, table_opt_.block_size_deviation,
+          sub_index_builder_->index_block_builder_));
       seperator_is_key_plus_seq_ = true;
     }
   }