KDP No Longer Accepts MOBI Files

It’s official. As of August 1, KDP no longer accepts files in the MOBI format. If you try to upload one, you’ll receive an error stating “Reflowable mobi input is not supported.”

Error message reading "Reflowable mobi input is not supported."

To publish your ebook with KDP, you’ll need to upload Vellum’s Kindle EPUB output. Details can be found in our earlier post: Changes at KDP.

New in Vellum: Streamlined PDFs for IngramSpark

With its wide reach and years of experience, IngramSpark is an important option for print-on-demand. 

That’s why we’re excited about Vellum 2.8.5, featuring an all-new PDF system that makes it easier to use IngramSpark for your paperbacks and hardcovers.


Vellum now creates files in the PDF/X-1a format, an industry standard for print-on-demand. That means the PDFs you create with Vellum will be immediately accepted by IngramSpark: no warnings, no waivers. (Though we still recommend ordering a proof!)

Vellum’s new PDF system is enabled for every PDF you create. No extra configuration is necessary. And Vellum’s PDFs still work great at Amazon KDP, the most popular option for print-on-demand.

Vellum 2.8.5 is a free update and requires macOS Mojave or newer.

To get Vellum 2.8.5, use Check for Updates. Or download Vellum from vellum.pub.

Changes at KDP: Vellum Has You Covered

As you may have heard, Amazon KDP will stop accepting MOBI files on June 28 August 1, 2021. Instead, you’ll need to upload your ebook in the EPUB format.

Vellum has you covered. In fact, we’ve been continually making changes to Vellum’s Kindle output as Amazon has moved away from MOBI files. Here are some tips for publishing or updating your ebook at KDP:

Make sure you are up-to-date

Use Check for Updates to confirm you have the latest version of Vellum (at time of writing: 2.8.4). Current versions of Vellum produce an EPUB file for Kindle, ready for KDP.

Upload Vellum’s Kindle output

When uploading your ebook to KDP, always use Vellum’s Kindle-specific EPUB file. (Vellum’s Generic EPUB output is not intended for Amazon.)

Use Kindle Previewer to review your book

To review your ebook before publishing, you can use Amazon’s Kindle Previewer tool, which will open EPUB files created for Kindle.

Vellum can still create a MOBI file

You’ll need an EPUB file for KDP, but you may still want a MOBI to send to an advance reader. If so, you can configure Kindle Ebook Formats to generate a Kindle.epub file for publishing and a Kindle.mobi file to send to readers.

Can’t update to 2.8? You have options

Vellum currently requires macOS Mojave or newer.

If your Mac is running Sierra or High Sierra, you won’t be able to update to Vellum 2.8. You still have the option to create an EPUB file in Preferences, though: you just won’t have the option to generate both at once.

If your Mac is using El Capitan, please contact us for options.

You’ll find more information about this change at Amazon in their FAQ.
Have a question not covered there? Let us know!

Update 6/28/21: Amazon has shifted this deadline from June 28 to August 1, 2021
Update 8/2/21: As promised, KDP no longer accepts mobi files

Vellum 2.8.4

Vellum 2.8.4 is a minor update that includes these improvements:

  • About the Author now allows longer Amazon Author URLs in print
  • Fixed a problem where the Text Editor would not use all available width
  • Restored missing Ebook-only and Print-only icons in Navigator
  • Addressed an issue with print layout for a coming Big Sur update
  • Improved compatibility for Kobo ebooks on older devices

This release is a free update, available now.

Vellum 2.8.3

Vellum 2.8.3 is a minor update with many improvements, including:

  • A new Vellum icon for macOS Big Sur
  • Improved reliability for page numbering in print editions
  • Consistent appearance for chapters with and without subheads in the TOC
  • Better compatibility importing files from Microsoft 365
  • Updated blockquote graphic to avoid issues with Enhanced Typesetting

This release is a free update, available now.

Vellum is Optimized for the M1

Vellum is now optimized for Apple’s M1, the chip found in new Macs arriving later this week. 

Vellum 2.8.2 is a universal app, so it will run natively on both existing Macs and on those using the new M1. And on the M1, Vellum is fast, with significant speedups for importing, previewing, and generating books. If you’ve purchased a new Mac, be sure to update to Vellum 2.8.2, available now.

Big Sur and New Macs

Apple has released macOS Big Sur, featuring a brand new look for your Mac. If you upgrade your Mac to Big Sur, make sure you’re running the latest version of Vellum (2.8.1), which has been updated for this new release of macOS. You can do that using Check for Updates.

Apple also announced brand new Macs featuring the all-new M1 processor. If you’re planning to purchase one of these new models, you can look forward to a version of Vellum optimized for the M1, coming early next week.

Update 11/17/20: Vellum 2.8.2 is now available, and is optimized for the M1.

Breaking News: Vellum 2.8 is Here!

Vellum 2.8 is here! With this release, you can insert page breaks, create an ebook call-to-action, and choose from updated options for Kindle output.

Page Breaks

With Vellum 2.8, you can now insert a Page Break within a chapter. Use page breaks to start each section on a new page, or end a chapter with a page of discussion questions or items for reflection.

In some cases, you may only want to keep a section title from the bottom of the page. If you’ve used an Alignment Block for the title, you can now enable Keep With Next Paragraph to ensure the title stays on the same page as the text that follows (just as a Subhead will).

Selecting Ebooks Only for a call-to-action at the end of a chapter

Ebook Calls-to-Action

If you end your final chapter with a quick call-to-action (like a newsletter signup or a request for a review), you may want to restrict this to your ebook edition. You can now mark text like this as Ebook Only using the new Include In menu for Alignment Blocks.

Options for EPUB Only and EPUB + MOBI Kindle generation.

New Kindle Output Options

To help you follow Amazon’s new recommendation for an EPUB file, Vellum now offers these updated options for Kindle output:

  • EPUB Only

With either option, Vellum will provide a Kindle-specific EPUB file that’s ready to upload to KDP. If you need to sideload onto a Kindle, Vellum can output a MOBI file as well.

If you’ve generated ebooks before, you’ll see the prompt above the next time you generate. You can also select from these options in Generation Preferences.

Also in Vellum 2.8

  • A new prompt to confirm chapters reordered via drag-and-drop
  • New commands to add chapters to Parts and Volumes
  • A fix for cases when Chapter 1 did not appear on the right side of a spread
  • More compatible ornament images for Kobo ebooks
  • Improved compatibility with the upcoming release of macOS Big Sur

Vellum 2.8 is a free update. This version requires macOS Mojave or newer.

To get Vellum 2.8, use Check for Updates in the Vellum menu. Or download and install Vellum from vellum.pub.