When you try to open an OCR project after FineReader PDF 15 update (Release 5) the following message occurs:

The OCR project was created in an earlier version of ABBYY FineReader 15. You can create a copy and convert it into a new OCR project. Copy and convert the OCR project?

You need to convert the OCR project in order to open it in the updated version of FineReader 15. This situation is connected with updated OCR technologies in FineReader 15.