I added a Value Transformer (subclass of NSSecureUnarchiveFromDataTransformer) to an existing "thumbnail" attribute that saves UIImage data as "Transformable"). The attribute had been using the "default" Transformer (ie. no transformer set) but warnings report this is insecure and will stop working at some point down the road... Anyhow, everything seems to be working fine (including with existing data), and the warnings are gone -- but just wanted to check if I need to create a new Core Data model version and migrate to it in this scenario. Attributes, data types, names, etc. all remain unchanged. The only modification is the addition of the custom NSSecureUnarchiveFromDataTransformer in the "Transformer" field. Thank you!