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KDP Accepted, Apple Books Rejected? Here's Why and How to Fix It

Fateh8 min read

You upload your EPUB to KDP, it goes live, everything looks fine. Then you try Apple Books Connect and get a rejection email. Same file. Different result.

This is one of the most frustrating things about wide publishing. Apple Books rejected your EPUB — not because it's a bad book, but because Apple has stricter technical requirements than Amazon. Understanding exactly why the same file passes one platform and fails another is the key to fixing it without guessing.

Why KDP Accepts Files That Apple Books Rejects

Amazon KDP doesn't read your EPUB the way Apple Books does. KDP converts your EPUB into its own internal format before publishing. During that conversion, it silently fixes or ignores many structural problems — unclosed tags, missing metadata, malformed OPF entries. KDP is designed to be forgiving because it transforms the file before delivery anyway.

Apple Books renders your EPUB directly. It's delivered to iOS and macOS devices as-is, which means every HTML error, every OPF problem, and every CSS conflict reaches the reader's device. Apple validates strictly because it has to — it can't silently repair problems that will break the reading experience on devices it doesn't control.

The same EPUB can fail Apple Books validation while passing KDP precisely because Amazon is doing repair work behind the scenes that Apple doesn't do. If your file has structural problems, KDP hides them from you. Apple doesn't.

What Apple Books Rejection Emails Actually Say

Apple's rejection messages are notoriously vague. Common rejection email text includes:

"Your book could not be delivered because it contains content
errors. Please review your file for formatting issues and resubmit."

"We were unable to process your submission. Your EPUB file
may contain invalid XML or structural errors."

"Your book's table of contents could not be detected.
Please ensure your EPUB contains a valid navigation document."

These messages tell you the category of the problem but not the specific file, line, or error. That's why running a validator before you submit is the only reliable way to know exactly what's wrong — Apple won't tell you with enough precision to fix it without additional tooling.

The 6 Most Common Reasons Apple Books Rejects EPUBs

1. Invalid or Missing EPUB 3.0 Metadata

Apple Books requires proper EPUB 3.0 metadata in the OPF file. This includes a valid unique identifier, the correct EPUB version declaration, and a conforming dc:language tag. EPUB 2.0 files and poorly formed metadata frequently trigger rejections.

Check your content.opf for this declaration at the top:

<package xmlns="http://www.idpf.org/2007/opf" version="3.0">

If it says version="2.0", your file needs to be rebuilt to EPUB 3.0 spec. Also check that dc:language uses a BCP 47 language tag like en or en-US — not the word "English" spelled out.

2. CSS That References External Resources

Apple Books blocks all external resource loading at the system level. If your CSS contains @import url("https://fonts.googleapis.com/...") or any other reference to an external stylesheet or font service, Apple will reject the file. All fonts and stylesheets must be fully embedded inside the EPUB package — no CDN fonts, no remote CSS, no external images loaded via CSS background-image.

3. Malformed XHTML in Chapter Files

Apple Books requires XHTML — not regular HTML. XHTML is stricter: every tag must be properly closed, attribute values must be quoted, and the file must be well-formed XML at every level. Common XHTML violations:

  • <br> instead of <br/>
  • <img src="..."> instead of <img src="..."/>
  • Unescaped & in text or URLs (must be &amp;)
  • Nested elements that violate HTML block/inline rules
  • Missing xmlns declaration on the root <html> element

A single unclosed tag is enough to cause a parse failure for the entire chapter file. Run your EPUB through the EPUB Validator to catch every malformed tag before uploading.

4. Missing or Incorrect Navigation Document

EPUB 3.0 requires an nav.xhtml navigation document in addition to the NCX file. This navigation document must include a <nav epub:type="toc"> element with an ordered list (<ol>) of links to every chapter. Many older conversion tools create only an NCX file (EPUB 2.0 format). Apple Books requires the EPUB 3.0 nav document, and the manifest item for it must have properties="nav".

The correct manifest entry looks like this:

<item id="nav" href="nav.xhtml"
  media-type="application/xhtml+xml"
  properties="nav"/>

5. Images That Exceed Size or Format Limits

Apple Books enforces strict image limits. Cover images over 4MB and interior images over 2MB frequently trigger rejections. High-resolution images from photography or illustration need compression before embedding. A 300 DPI image at full quality for print is almost always too large for ebook delivery.

Format matters too. Apple Books supports JPEG, PNG, GIF, and SVG. WEBP images are not reliably supported and may cause rejections on older iOS versions. If you have WEBP images in your EPUB, convert them to JPEG or PNG first.

6. Incorrect Mimetype File

Every EPUB must contain a mimetype file as the very first file in the ZIP archive, stored without compression, containing exactly the text application/epub+zip with no trailing newline. If the mimetype file is compressed, out of order, or has extra whitespace, Apple Books rejects the file immediately — often with a vague error that doesn't mention mimetype at all.

How to Diagnose and Fix an Apple Books Rejection: Step by Step

  1. Get a detailed validation report. Upload your EPUB to the BookKraft AI EPUB Validator. It runs the same structural checks Apple Books uses and gives you a line-by-line breakdown of every problem. Save the full report before making any changes.
  2. Fix XHTML errors first. These are the most common cause of Apple rejections. Work through the list of HTML errors the validator reports. Each one shows the filename and line number — open that file in a text editor and fix the specific error.
  3. Check and fix the nav document. Look for nav.xhtml in your EPUB. Open it and confirm it has a <nav epub:type="toc"> element with chapter links. If it's missing, the TOC Generator can rebuild it from your chapter headings.
  4. Remove external CSS and font references. Search your CSS files for any @import url( pointing to external resources. Replace with embedded fonts or system fonts.
  5. Compress large images. For any image over 2MB in your EPUB, open it in an image editor and compress. For JPEGs, 85% quality at 96 DPI is the right target. For the cover, aim under 3MB at 1400x2100px minimum.
  6. Verify the mimetype file. Unzip your EPUB and check that mimetype is the first entry in the ZIP (open the ZIP in a hex editor or use a ZIP inspection tool). If it's compressed or out of order, repackage using an EPUB-aware tool.
  7. Revalidate and confirm zero errors. After making fixes, upload to the validator again. Don't resubmit to Apple Books until the validator shows no errors — the same validation rules apply.

Pro Tips for Apple Books Submission

  • Target EPUB 3.0 from the start. If you're using a tool that only outputs EPUB 2.0, switch tools. EPUB 3.0 is the standard Apple Books is optimized for, and EPUB 2.0 files need extra attention to pass Apple's validation.
  • Test on an actual Apple device before submitting. Sideload your EPUB to an iPhone or iPad via the Files app and open it in Apple Books. If it opens cleanly with correct formatting and a working TOC, it's structurally sound enough to submit through Books Connect.
  • Don't use Word's built-in EPUB export. Microsoft Word's EPUB export produces files with significant structural issues — ghost spacing, excessive inline styles, and often broken XHTML. Convert from Word to a clean format using a dedicated tool instead.
  • Match metadata between EPUB and Books Connect. Your OPF title, author, and ISBN must match what you enter in Apple Books Connect. Mismatches trigger ingestion errors even when the EPUB validates cleanly.

Frequently Asked Questions

Does Apple Books tell you exactly why an EPUB was rejected?

Rarely. The rejection email gives a category (metadata error, content error, structural error) but almost never specifies which file or line caused the problem. Using a validator before uploading is the only reliable way to get specific, actionable error information — Apple's emails won't give you enough detail to fix the problem without additional tooling.

Can I use the same EPUB file for both KDP and Apple Books?

Yes, if the EPUB is properly formed to EPUB 3.0 spec. A high-quality EPUB 3.0 file works across all major platforms. The catch is that KDP's tolerance for errors makes it easy to publish a file that isn't actually valid — and you only discover this when Apple Books rejects it. Build to EPUB 3.0 spec from the start and validate before submitting anywhere.

How long does Apple Books review take after fixing errors?

Usually 24–72 hours for new submissions after a fix. If you've had multiple rejections on the same ISBN or title, the review queue may take longer. The fastest path through review is fixing all validation errors — not just the ones mentioned in the rejection — before resubmitting. Submitting an EPUB that still has other unrelated errors will just generate another rejection cycle.

Is EPUB 2.0 still accepted by Apple Books?

Apple Books technically supports EPUB 2.0, but many EPUB 2.0 files fail validation because they were created by tools that weren't strict about spec compliance. EPUB 3.0 is safer — it's what Apple Books is optimized for, and modern formatting tools all output EPUB 3.0. If you have an EPUB 2.0 file that keeps getting rejected, rebuilding it to EPUB 3.0 spec is usually faster than trying to patch all the individual EPUB 2.0 issues.

Do I need separate metadata for Apple Books vs KDP?

The metadata inside your EPUB OPF file is used for ingestion, but Apple Books Connect and KDP both have their own metadata entry fields. The critical requirement is consistency: make sure your title, author name, and ISBN match between your EPUB OPF and your platform listings. Mismatches between what's in the file and what's in the platform's database cause ingestion errors that show up separately from EPUB validation errors. The Metadata Builder generates correctly formatted metadata for both platforms simultaneously to prevent these mismatches.

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