diff --git a/product/ERP5/Document/BusinessTemplate.py b/product/ERP5/Document/BusinessTemplate.py
index 7ce227aaa9a2e1b5a47a16525905c985f380c71f..0f904afb7deaf91d44d93d3cda058af9554d69e6 100644
--- a/product/ERP5/Document/BusinessTemplate.py
+++ b/product/ERP5/Document/BusinessTemplate.py
@@ -575,7 +575,8 @@ class BaseTemplateItem(Implicit, Persistent):
 
     attr_set = {'_dav_writelocks', '_filepath', '_owner', '_related_index',
                 'last_id', 'uid',
-                '__ac_local_roles__', '__ac_local_roles_group_id_dict__'}
+                '__ac_local_roles__', '__ac_local_roles_group_id_dict__',
+                '_erp5_coverage_filename'}
     if export:
       if keep_workflow_history_last_history_only:
         self._removeAllButLastWorkflowHistory(obj)