diff --git a/be/src/exec/schema_scanner.cpp b/be/src/exec/schema_scanner.cpp
index 85199f2a0be6f6..5892b064c52b9b 100644
--- a/be/src/exec/schema_scanner.cpp
+++ b/be/src/exec/schema_scanner.cpp
@@ -119,12 +119,12 @@ Status SchemaScanner::get_next_block_async(RuntimeState* state) {
     auto task_ctx = state->get_task_execution_context();
     RETURN_IF_ERROR(ExecEnv::GetInstance()->fragment_mgr()->get_thread_pool()->submit_func(
             [this, task_ctx, state]() {
-                DCHECK(_async_thread_running == false);
                 auto task_lock = task_ctx.lock();
                 if (task_lock == nullptr) {
                     _scanner_status.update(Status::InternalError("Task context not exists!"));
                     return;
                 }
+                DCHECK(_async_thread_running == false);
                 SCOPED_ATTACH_TASK(state);
                 _dependency->block();
                 _async_thread_running = true;