diff --git a/apps/worker/worker_app/tasks/generation.py b/apps/worker/worker_app/tasks/generation.py
index b628bf21b..33981b8ff 100644
--- a/apps/worker/worker_app/tasks/generation.py
+++ b/apps/worker/worker_app/tasks/generation.py
@@ -1555,6 +1555,7 @@ def generate_video(self, task_id: str) -> dict:
 
             # 持久化封面 URL 到 GenerationTask（统一封面管道：从渲染后视频抽帧）
             if cover_url:
+                _cover_session = None
                 try:
                     _cover_session = SessionLocal()
                     try:
@@ -1572,7 +1573,8 @@ def generate_video(self, task_id: str) -> dict:
                                 cover_url[:80],
                             )
                     finally:
-                        _cover_session.close()
+                        if _cover_session:
+                            _cover_session.close()
                 except Exception as cover_err:
                     logger.warning(
                         "[task_id=%s] 封面URL持久化失败（不影响主流程）: %s",