diff --git a/programs/server/Server.cpp b/programs/server/Server.cpp
index 300698b4439..8ea3954b493 100644
--- a/programs/server/Server.cpp
+++ b/programs/server/Server.cpp
@@ -297,6 +297,11 @@ int Server::main(const std::vector<std::string> & /*args*/)
     global_context->makeGlobalContext();
     global_context->setApplicationType(Context::ApplicationType::SERVER);
 
+    // Initialize global thread pool. Do it before we fetch configs from zookeeper
+    // nodes (`from_zk`), because ZooKeeper interface uses the pool. We will
+    // ignore `max_thread_pool_size` in configs we fetch from ZK, but oh well.
+    GlobalThreadPool::initialize(config().getUInt("max_thread_pool_size", 10000));
+
     bool has_zookeeper = config().has("zookeeper");
 
     zkutil::ZooKeeperNodeCache main_config_zk_node_cache([&] { return global_context->getZooKeeper(); });
@@ -436,9 +441,6 @@ int Server::main(const std::vector<std::string> & /*args*/)
     DateLUT::instance();
     LOG_TRACE(log, "Initialized DateLUT with time zone '{}'.", DateLUT::instance().getTimeZone());
 
-    /// Initialize global thread pool
-    GlobalThreadPool::initialize(config().getUInt("max_thread_pool_size", 10000));
-
     /// Storage with temporary data for processing of heavy queries.
     {
         std::string tmp_path = config().getString("tmp_path", path + "tmp/");
diff --git a/src/Common/ThreadPool.cpp b/src/Common/ThreadPool.cpp
index 56198b97be5..dda16c7725d 100644
--- a/src/Common/ThreadPool.cpp
+++ b/src/Common/ThreadPool.cpp
@@ -13,6 +13,7 @@ namespace DB
     namespace ErrorCodes
     {
         extern const int CANNOT_SCHEDULE_TASK;
+        extern const int LOGICAL_ERROR;
     }
 }
 
@@ -277,7 +278,11 @@ std::unique_ptr<GlobalThreadPool> GlobalThreadPool::the_instance;
 
 void GlobalThreadPool::initialize(size_t max_threads)
 {
-    assert(!the_instance);
+    if (the_instance)
+    {
+        throw DB::Exception(DB::ErrorCodes::LOGICAL_ERROR,
+            "The global thread pool is initialized twice");
+    }
 
     the_instance.reset(new GlobalThreadPool(max_threads,
         1000 /*max_free_threads*/, 10000 /*max_queue_size*/,