Recently, someone complaint about being unable to refresh his product. After the first refresh, he was unable create new instances of his product. He got an unintelligent error message: "AttributeError: None object does not have attribute _setObject" I just found out why this happens: Products using old style initializations install their constructors as methods of "Folder.Folder". When the product is reinstalled during a refresh, then in "OFS.Application.install_product" it is checked whether "Folder.Folder" already has the method. It has! The old method from the time before the refresh. Therefore, the old constructors remain installed. I do not yet understand, why a "self" that should be a folder is passed as None, but I am convinced it has to do with the outdated constructor in "Folder.Folder". Upgrading to new style initialization works around the problem. Dieter