Thank you for using Epubor Kindle transfer. Please check what's the kindle version you are using now. If it is the kindle version 1.25, you need to downgrade it to the older version to get your problem fixed. Please follow this guide: https://www.epubor.com/faq.html#e107 Also, we will contact you via email to help you fix your problem.
Got the message failed to transfer, but that is not enogh information to solve the problem. I have just downloaded the latest upgrade.
HarryK4510@Gmail.com