diff --git a/app/models/property.rb b/app/models/property.rb
index a4f4935..917f878 100644
--- a/app/models/property.rb
+++ b/app/models/property.rb
@@ -113,6 +113,7 @@ class Property
   end
   before_save do
     unless @no_validate
+      self.custom_field_names = [] if self.custom_field_names.nil?
       self.default_field_names = self.get_all_fields(true)
       self.class::FIELDSNAME.each do |f|
         if((self.send(f)["enable"]  == "1" rescue true) && !(self.custom_field_names.include?(f)))