diff --git a/CMakeModules/cpp_graphql_gen.cmake b/CMakeModules/cpp_graphql_gen.cmake
index 1ee15d1f86..74fbabdcf3 100644
--- a/CMakeModules/cpp_graphql_gen.cmake
+++ b/CMakeModules/cpp_graphql_gen.cmake
@@ -6,7 +6,7 @@ set(Boost_NO_WARN_NEW_VERSIONS 1)
 FetchContent_Declare(
   cppgraphqlgen
   GIT_REPOSITORY https://github.com/microsoft/cppgraphqlgen.git
-  GIT_TAG 8c1623acc42392ef2a1bc0336482621386f98c77 # v4.5.0
+  GIT_TAG 1d659227bfc51fb7d9bb5dc9862234e7cfd1b1e3 # v4.5.4
 )
 set(GRAPHQL_BUILD_TESTS OFF)
 set(GRAPHQL_UPDATE_VERSION OFF)
diff --git a/libraries/core_libs/network/graphql/include/graphql/types/dag_block.hpp b/libraries/core_libs/network/graphql/include/graphql/types/dag_block.hpp
index 6ef037d513..3bb2f1a6a8 100644
--- a/libraries/core_libs/network/graphql/include/graphql/types/dag_block.hpp
+++ b/libraries/core_libs/network/graphql/include/graphql/types/dag_block.hpp
@@ -1,5 +1,7 @@
 #pragma once
 
+#include <mutex>
+
 #include "DagBlockObject.h"
 #include "final_chain/final_chain.hpp"
 #include "pbft/pbft_manager.hpp"
@@ -34,6 +36,7 @@ class DagBlock {
   std::shared_ptr<::taraxa::TransactionManager> transaction_manager_;
   std::function<std::shared_ptr<object::Block>(::taraxa::EthBlockNumber)> get_block_by_num_;
 
+  mutable std::mutex mu_;
   mutable std::optional<uint64_t> period_;
 };
 
diff --git a/libraries/core_libs/network/graphql/src/query.cpp b/libraries/core_libs/network/graphql/src/query.cpp
index 9afae748f1..a64245a567 100644
--- a/libraries/core_libs/network/graphql/src/query.cpp
+++ b/libraries/core_libs/network/graphql/src/query.cpp
@@ -43,8 +43,14 @@ std::shared_ptr<object::Block> Query::getBlock(std::optional<response::Value>&&
   }
   if (hash) {
     block_number = final_chain_->block_number(dev::h256(hash->get<std::string>()));
+    if (!block_number) {
+      return nullptr;
+    }
   }
   auto block_header = final_chain_->block_header(block_number);
+  if (!block_header) {
+    return nullptr;
+  }
 
   auto pbft_block = db_->getPbftBlock(block_header->number);
   if (!pbft_block) {
diff --git a/libraries/core_libs/network/graphql/src/types/dag_block.cpp b/libraries/core_libs/network/graphql/src/types/dag_block.cpp
index a9b1c78a81..0d6d9d9721 100644
--- a/libraries/core_libs/network/graphql/src/types/dag_block.cpp
+++ b/libraries/core_libs/network/graphql/src/types/dag_block.cpp
@@ -37,6 +37,7 @@ response::Value DagBlock::getLevel() const noexcept {
 }
 
 std::optional<response::Value> DagBlock::getPbftPeriod() const noexcept {
+  std::lock_guard<std::mutex> lock{mu_};
   if (period_) {
     return response::Value(static_cast<int>(*period_));
   }
@@ -49,6 +50,7 @@ std::optional<response::Value> DagBlock::getPbftPeriod() const noexcept {
 }
 
 std::shared_ptr<object::Account> DagBlock::getAuthor() const noexcept {
+  std::lock_guard<std::mutex> lock{mu_};
   if (!period_) {
     const auto [has_period, period] = pbft_manager_->getDagBlockPeriod(::taraxa::blk_hash_t(dag_block_->getHash()));
     if (has_period) {