OK, I finally dug far enough through the list archives to find a suggestion that worked. My old Zope had lots of products installed. I wasn't using a lot of them, so I didn't install them into the new Zope. To solve the problem, I had to delete from the database the products that were no longer installed. To be able to delete ZDiscussions (I think it was), I had to actually copy Products/ZDBase into the new installation. Then I could delete the products that depended on it. Now that the database no longer refers to products which are no longer installed, all is well. I seem to remember a comment somewhere, saying that this was on DC's radar as something to fix. Please :-) Thanks, Doug - - - - - Hi, I just updated from Zope 2.0.1 to 2.1.6. All of the Python-based products I was using previously have been migrated successfully. But I have a number of products that I created with ZClasses. I can examine these products in the control panel, and everything is there and looks fine, but all of these classes' object instances are broken. I get this message when clicking on one in the management interface: "This object is broken because the unknown product that created it is no longer installed or is installed incorrectly. Please contact your product vendor for assistance." "Note that the data associated with this product has not been lost, and will be accessible again if the product is reinstalled." I'll keep digging for documentation I may have missed, but I'd really appreciate some help. Doug (would appreciate copies by private email as I am on the digest) -- Doug Wyatt doug@sonosphere.com http://www.sonosphere.com/