Amazon KDP Unsupported Fonts Error: Why It Happens and How to Fix It

If you’re a self-published author trying to upload minor corrections to a book that’s been live on Amazon for months—or even years—and suddenly seeing an error about unsupported fonts, you’re not alone.

No, you didn’t suddenly break your book.

Amazon KDP has quietly changed how it validates fonts during the Quality Check process, and it’s catching a lot of previously approved interiors off guard.

Let’s talk about what’s actually going on, and what to do next.

Why Amazon KDP Is Suddenly Flagging Fonts That Worked Before

Here’s the frustrating truth: When you upload any new interior file to KDP—even for a small typo fix—Amazon re-checks the entire manuscript as if it’s a brand-new book.

That means:

• Fonts that passed before are re-evaluated

• Embedded fonts are re-scanned

• Older formatting choices are held to new standards

So even if:

• your book has been live for years

• the font is embedded in the PDF

• nothing about the design changed

…it can still fail the Quality Check.

This is especially common with fonts like Lucida Sans, Lucida Sans Demi, and other system or legacy fonts that Word and older templates love to sneak in (and these are the exact fonts that tripped me up for a time this morning with a client's manuscript!).

The Most Common KDP Error Message Authors Are Seeing

Many authors report seeing a message like:

“Unsupported fonts are used in your file. Please create a new interior file with [font name] replaced.”

The problem? Amazon doesn’t tell you where that font is being used. And in many cases, it’s not in your main body text at all.

Where Unsupported Fonts Are Usually Hiding in Word Manuscripts

If you used Microsoft Word to format your interior, unsupported fonts are almost always hiding in places authors understandably don’t even think to check:

• Page numbers (headers or footers)

• Table of Contents

• Bullets or special characters

• Section breaks

• Imported text from older Word documents

• Default Word styles you never manually changed

This is why so many authors feel stuck—everything looks correct, but the font is still embedded somewhere.

This Is Not a “You Did Something Wrong” Problem

This is important to understand:

This issue is not caused by "beginner mistakes." I've loaded 100+ books to KDP, and, as mentioned, this tripped me up for hours this morning!

It’s happening because:

• Amazon updated font validation rules

• Older fonts are no longer reliably accepted

• Word embeds fonts in inconsistent ways

• KDP’s error reporting is vague (at best)

Even professionally formatted books are getting flagged.

The Safest Way to Fix Unsupported Font Errors on Amazon KDP

While it’s technically possible to try forcing full font embedding, the most reliable fix is:

➡️ Replace the unsupported font entirely with a KDP-safe font

Fonts that consistently pass KDP checks (at least today) include:

• Arial

• Times New Roman

• Open Sans

• Lato

• Garamond

This does not require reformatting your entire book. When done correctly, it’s a controlled, global change.

Watch: How to Find and Fix Unsupported Fonts in Word (Without Reformatting Your Book)

In this video, I walk you through:

• How to locate hidden fonts in Microsoft Word

• How to replace them globally (even when Word doesn’t make it obvious)

• The exact places authors forget to check

• How to ensure no additional formatting glitches occur as a result so you can upload a clean PDF to KDP

This is the same process I use for my own books and client projects.

How to Avoid This Problem in the Future

If you plan to update your book again later, a few preventative steps help:

• Use KDP-safe fonts from the beginning, whenever possible

• Avoid system fonts that rely on licensing quirks

• Replace fonts globally before exporting PDFs

• Always check PDF → File Properties → Fonts before uploading to ensure that your fonts are embedded (even though this doesn't always prevent KDP from rejecting a file with fonts it no longer supports)

These small steps can save you hours of frustration later.