We are sincerely sorry for this issue. Please deregister it from your old kindle for pc and then download your kindle books via kindle for pc 2.7 again. Also, please ensure you are using the latest version of Epubor Ultimate again. You can download it here: https://www.epubor.com/ultimate-download.htm#os_Win If this issue still persists, please screenshot the error message and send it to us.
