diff --git a/runtime/datamate-python/app/module/annotation/interface/project.py b/runtime/datamate-python/app/module/annotation/interface/project.py
index 1cd0ce5..efe6121 100644
--- a/runtime/datamate-python/app/module/annotation/interface/project.py
+++ b/runtime/datamate-python/app/module/annotation/interface/project.py
@@ -225,8 +225,9 @@ async def get_mapping(
     except HTTPException:
         raise
     except Exception as e:
-        logger.error(f"Error getting mapping: {e}")
-        raise HTTPException(status_code=500, detail="Internal server error")
+        import traceback
+        logger.error(f"Error getting mapping: {e}\n{traceback.format_exc()}")
+        raise HTTPException(status_code=500, detail=f"Internal server error: {str(e)}")
 
 @router.get("/by-source/{dataset_id}", response_model=StandardResponse[PaginatedData[DatasetMappingResponse]])
 async def get_mappings_by_source(
diff --git a/runtime/datamate-python/app/module/annotation/service/mapping.py b/runtime/datamate-python/app/module/annotation/service/mapping.py
index 18b788a..7be5bee 100644
--- a/runtime/datamate-python/app/module/annotation/service/mapping.py
+++ b/runtime/datamate-python/app/module/annotation/service/mapping.py
@@ -49,13 +49,21 @@ class DatasetMappingService:
         mapping = row[0]  # LabelingProject object
         dataset_name = row[1]  # dataset_name from join
 
+        logger.debug(f"_to_response_from_row: mapping.id={mapping.id}")
+
         # Get template_id from mapping
         template_id = getattr(mapping, 'template_id', None)
 
         # 从 configuration JSON 字段中提取 label_config 和 description
         configuration = getattr(mapping, 'configuration', None) or {}
-        label_config = configuration.get('label_config') if isinstance(configuration, dict) else None
-        description = configuration.get('description') if isinstance(configuration, dict) else None
+        logger.debug(f"_to_response_from_row: configuration type={type(configuration)}, value={configuration}")
+
+        label_config = None
+        description = None
+        if isinstance(configuration, dict):
+            label_config = configuration.get('label_config')
+            description = configuration.get('description')
+        logger.debug(f"_to_response_from_row: label_config={label_config[:100] if label_config else None}...")
 
         # Optionally fetch full template details
         template_response = None
@@ -94,6 +102,8 @@ class DatasetMappingService:
             mapping: LabelingProject ORM object
             include_template: If True, fetch and include full template details
         """
+        logger.debug(f"_to_response: mapping.id={mapping.id}")
+
         # Fetch dataset name
         dataset_name = None
         dataset_id = getattr(mapping, 'dataset_id', None)
@@ -108,8 +118,14 @@ class DatasetMappingService:
 
         # 从 configuration JSON 字段中提取 label_config 和 description
         configuration = getattr(mapping, 'configuration', None) or {}
-        label_config = configuration.get('label_config') if isinstance(configuration, dict) else None
-        description = configuration.get('description') if isinstance(configuration, dict) else None
+        logger.debug(f"_to_response: configuration type={type(configuration)}, value={configuration}")
+
+        label_config = None
+        description = None
+        if isinstance(configuration, dict):
+            label_config = configuration.get('label_config')
+            description = configuration.get('description')
+        logger.debug(f"_to_response: label_config={label_config[:100] if label_config else None}...")
 
         # Optionally fetch full template details
         template_response = None
@@ -135,6 +151,7 @@ class DatasetMappingService:
             "deleted_at": mapping.deleted_at,
         }
 
+        logger.debug(f"_to_response: response_data keys={response_data.keys()}")
         return DatasetMappingResponse(**response_data)
     
     async def create_mapping(