diff --git a/frontend/mobile-app/lib/core/network/api_client.dart b/frontend/mobile-app/lib/core/network/api_client.dart
index 939dc3ed..6eb1305d 100644
--- a/frontend/mobile-app/lib/core/network/api_client.dart
+++ b/frontend/mobile-app/lib/core/network/api_client.dart
@@ -384,7 +384,10 @@ class ApiClient {
       case DioExceptionType.badResponse:
         final statusCode = error.response?.statusCode;
         final data = error.response?.data;
-        final message = data is Map ? data['message'] ?? '请求失败' : '请求失败';
+        final rawMsg = data is Map ? data['message'] : null;
+        final message = rawMsg is List
+            ? (rawMsg as List).join(', ')
+            : (rawMsg?.toString() ?? '请求失败');
 
         switch (statusCode) {
           case 400:
diff --git a/frontend/mobile-app/lib/features/pre_planting/presentation/pages/pre_planting_purchase_page.dart b/frontend/mobile-app/lib/features/pre_planting/presentation/pages/pre_planting_purchase_page.dart
index b507f02d..d0eb3215 100644
--- a/frontend/mobile-app/lib/features/pre_planting/presentation/pages/pre_planting_purchase_page.dart
+++ b/frontend/mobile-app/lib/features/pre_planting/presentation/pages/pre_planting_purchase_page.dart
@@ -351,10 +351,10 @@ class _PrePlantingPurchasePageState
       final response = await prePlantingService.createOrder(
         portionCount: _quantity,
         // 首次购买时传省市信息，续购时后端自动复用
-        provinceCode: _isFirstPurchase ? _selectedProvinceCode : null,
-        provinceName: _isFirstPurchase ? _selectedProvinceName : null,
-        cityCode: _isFirstPurchase ? _selectedCityCode : null,
-        cityName: _isFirstPurchase ? _selectedCityName : null,
+        provinceCode: _isFirstPurchase ? _selectedProvinceCode : _position?.provinceCode,
+        provinceName: _isFirstPurchase ? _selectedProvinceName : _position?.provinceName,
+        cityCode: _isFirstPurchase ? _selectedCityCode : _position?.cityCode,
+        cityName: _isFirstPurchase ? _selectedCityName : _position?.cityName,
       );
 
       debugPrint(