diff --git a/video-gen-api/app/middleware/request_encrypt.py b/video-gen-api/app/middleware/request_encrypt.py
index 0d4113ed..06e6a6ac 100644
--- a/video-gen-api/app/middleware/request_encrypt.py
+++ b/video-gen-api/app/middleware/request_encrypt.py
@@ -3,7 +3,7 @@ import json
 import logging
 
 from cryptography.hazmat.primitives.ciphers.aead import AESGCM
-from fastapi import Request, Response
+from fastapi import HTTPException, Request, Response
 from starlette.middleware.base import BaseHTTPMiddleware, RequestResponseEndpoint
 
 from app.config import settings
@@ -98,6 +98,14 @@ class RequestEncryptMiddleware(BaseHTTPMiddleware):
                 status_code=response.status_code,
                 headers={"X-Encrypted": "true", "Content-Type": "application/json"},
             )
+        except HTTPException as http_exc:
+            # BaseHTTPMiddleware 中 call_next 抛出的 HTTPException 会直接传播，
+            # 这里捕获后返回对应状态码的响应，避免被外层 except Exception 吞掉
+            return Response(
+                content=json.dumps({"detail": http_exc.detail}, ensure_ascii=False),
+                status_code=http_exc.status_code,
+                headers={"Content-Type": "application/json"},
+            )
         except Exception:
             logger.exception("Request decryption failed")
             return Response(
diff --git a/video-gen-api/app/services/invoice.py b/video-gen-api/app/services/invoice.py
index 614d2b2a..8164519c 100644
--- a/video-gen-api/app/services/invoice.py
+++ b/video-gen-api/app/services/invoice.py
@@ -93,7 +93,7 @@ async def create_invoice(
             for o in occupied
         )
         raise HTTPException(
-            status_code=status.HTTP_400_BAD_REQUEST,
+            status_code=status.HTTP_409_CONFLICT,
             detail=details,
         )