diff --git a/be/src/olap/tablet_manager.cpp b/be/src/olap/tablet_manager.cpp
index 176dbfe6a34574..7006cd02770857 100755
--- a/be/src/olap/tablet_manager.cpp
+++ b/be/src/olap/tablet_manager.cpp
@@ -258,6 +258,10 @@ void TabletManager::cancel_unfinished_schema_change() {
                 return;
             }
 
+            if (new_alter_task == nullptr) {
+                continue;
+            }
+
             res = new_tablet->set_alter_state(ALTER_FAILED);
             if (res != OLAP_SUCCESS) {
                 LOG(FATAL) << "fail to save new tablet meta. res=" << res