Kindle KFX DRM Remove Failed and Solution

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As the Amazon wants to build its own digital ecosystem, employing Kindle KFX DRM to all books becomes a trending. As more and more Kindle been are encrypted by Kindle KFX DRM, Epubor Ultimate has been released as the first tool on the market can strip Kindle KFX DRM. Because of some user's mal-operation, some of you many come across the "Kindle KFX DRM Remove failed" issue. In this article, I will analyze the situations you may encounter and give you a resolution.

Pre-conditions to Remove Kindle KFX DRM

1, The Kindle eBooks should be purchased by your own account.

The first and most important thing you have to remember is that the eBooks you want to remove the DRM should be purchased via your own Amazon Account.

2, Please register your Kindle for PC/MAC or plug in your Kindle device before running Epubor Ultimate

If you are using the Kindle for PC/MAC to download the Kindle KFX books, please ensure your Kindle for PC/MAC are registered even if you have finished the downloading. If you really want to de-register your Kindle for PC/MAC on your computer, you can do it after the DRM has been removed from your Kindle books.

Epubor Ultimate can handle books downloaded via Kindle device, not including Kindle Fire Tablet, but only Kindle e-ink devices. In this situation, you only have to plug your Kindle device to your computer. Then the Epubor Ultimate will detect the Kindle Serial Number and use it to generate key to decrypt your Kindle books.

Can Epubor Ultimate handle Kindle Books Copied from your friends?

Usually, we do not suggest you copy the books from your friends. If you really want to, please register your friends's Kindle account at your Kindle for PC/MAC on your computer and then download the book you want. Then use Epubor Ultimate to remove the DRM. Please remember you have to keep the Kindle for PC/MAC in registeration with your friend's account information until this book has been decrypted.

3, Please ensure the Kindle KFX ebook information is complete.

The big difference between Kindle old format and the Kindle KFX format is the Kindle KFX format is consisted of a series of files and stored in one folder. So if you want to remove DRM from Kindle KFX ebooks, please ensure your have the while Kindle KFX eBook folder, not only a file with the extension of azw or kfx.

4, Computer system user name contains special characters.

 There’re some special characters in your computer system username (space, hyphen, underscore, dot, Chinese, Japanese, etc.) which may result in generating a wrong Kindle Key file. If you are failed to remove Kindle KFX DRM, please check your computer system username at first.

In this situation, you need to create a new system username for your PC/Mac, and this username only contains English letters and digital numbers like “allen” or “allen2018”. After creating a new system username, please install Kindle for PC/Mac, sync all books of this user, and run Epubor software to remove the DRM.

Or you can revise your username to ensure it only contains English letters. After that, de-register your Kindle for PC/MAC, and delete all downloaded books. Then register it again and re-sync all books.  Run Epubor software to remove the DRM.

5, What Kind of Kindle books are not supported by Epubor Ultimate?

Sample books--The books are titled like XXXEBSP.KFX or XXXEBSP.AZW are not supported. Epubor Ultimate are not promise to support sample books, but can handle some of them.

Rented books--If you rent this book, you may fail to remove the DRM from this Kind of eBooks.

Books get from Kindle Unlimited subscription--Many users have purchased the Kindle unlimited subscription service. Of course you can download many book freely, but do not try to use Epubor Ultimate to remove DRM from this kind of ebooks. You are not the owner of these books, but just can read them in the subscription time. It is another kind of rented books.

If the above 5 situations are not applied to you, you can also try the below method to solve your "Kindle KFX DRM Remove failed" issue.

Remove Kindle KFX DRM--Solution for Windows

Step 1. Clear the cache of Epubor Ultimate

Please delete the .ultimate folder. You can find it here: C:\Users\username\AppData\Roaming\.Ultimate.

Step 2. Delete the Epubor keys

Please delete Epubor_keys folder. You can find it here: C:\Users\username\.Epubor_Keys.

Step 3. Run Epubor Ultimate to remove the DRM


When you have downloaded the Epubor Ultimate for Windows, double click it to install it on your computer. When you open it, your downloaded Kindle books will be automatically detected and displayed on the left column. To remove the Kindle KFX DRM, you just have to drag the books from the left column to the right column. All Kindle books will be decrypted successfully.

If you are failed again, please delete the failed books and redownload them again. Run Epubor software to remove the DRM.

Remove Kindle KFX DRM--Solution for Mac

If you are using the Mac, there will be a slight different from Windows.

Step 1. Clear the cache of the Epubor Ultimate

Copy and paste this command to your terminal rm -rf ~/.Ultimate and then press on enter. If you are using other Epubor software, please change .Ultimate to .alldrmremoval or.kindledrmremoval.

Step 2. Delete all content Kindle content folder

Open terminal, and then copy this command rm -rf ~/Library/Application\ Support/Kindle/storage to the terminal and then press on “enter" to delete all files in Kindle content folder.

Open the terminal and copy the following command to the terminal rm -rf ~/Library/Containers/com.amazon.Kindle/Data/Library/Application\ Support/Kindle/storage and then press on “enter”.

Then copy this command rm -rf ~/Library/Application\ Support/Kindle and press on “enter” again.

If you have changed the directory of Kindle content folder, you have to find the folder and delete all the files manually.

Step 3. Delete Epubor Key files

Please also delete the Epubor Key file at your Mac. You can find it here: You can find the Epubor Key files here: Mac: /Users/system user/.Epubor_Keys/

Step 4. Redownload the books and run Epubor software to remove the DRM


Now you only have to re-sync your Kindle books and run Epubor Ultimate to remove the DRM.

Ultimate way to remove the Kindle KFX DRM

If above solutions can not fix your problem, why no download the Kindle books directly from the Amazon website as AZW3 format and remove the DRM. An article on our website has given you detailed guide about removing Kindle AZW3 DRM--How to Remove DRM From AZW3 eBook Files. I am sure you will get your problem fixed by this method.

If the all above mentioned solutions can not fix your issues, please feel free to contact Epubor Customer Service Center via email: support@epubor.com. We will get back to you with the solution within 24 hours.


joined Epubor since 2017. She always wants to share everything related to ebook reading and improve your reading journey.

08/6/2017 13:49:15
Never going to happen! I will never follow such a ridiculously inconvenient procedure simply to make your program function.  A MUCH better solution is for Epubor to FIX YOUR SOFTWARE so that it works without my having to downgrade my Kindle app, erase 600+ books, reinstall Kindle software, load each of those 600+ books again, then run your program.  If you think that's going to happen you're smoking some really funny mushrooms!
08/9/2017 09:23:18
You are welcome. We are glad to know it works for you!
11/29/2017 14:12:51
...What he said. I'm not going to downgrade and remove all my purchased books just so your softtware will work. I will wait until either a solution is found - or, that Amazon has finally found a way to encrypt content that is unbreakable, and we're all screwed.
12/11/2017 15:09:45
If you like, please contact our customer service about your problem. We can connect your computer to solve your problem directly via TEAM VIEWER
01/13/2018 13:29:07

I downgraded Kindle to the older version but still could convert 3 of the Kindle books to PDF.  Help, please.

I sent diagnostic from cao.tuyet.van@gmail.com with the error messages earlier.


01/15/2018 11:50:29
Thank you for contacting us. One of my colleague has received your email and will guide you to solve  the problem.
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