After updating to UPK 12 a common error when copying over style sheets, is that when it asks you to update your style sheets when you publish only to get the error that not all style sheets have been copied over. What’s happening is there have been some features that were not reinstated and UPK is searching for the style sheet for all document output types, but standalone topic publishing is no longer available so those style sheets won’t be transferred and thus produce the error. So just click okay and it should publish fine otherwise.
