Cermify · Error Library · KDP

Navigation · E-NCX

Missing or mismatched NCX / nav document

Kindle needs a table-of-contents navigation file (NCX for EPUB 2, nav doc for EPUB 3). Yours is missing or doesn't match your chapter headings.

Severity
error
Automatic repair
Supported
Submission impact
KDP: reject
Rule ID
E-NCX
Error: Missing or mismatched NCX / nav document
Category: Navigation
Severity: error
Auto Repair: Supported
Rule ID: E-NCX
Affected: KDP=reject, Apple=reject, Google=reject, Kobo=warning
Check this automatically with Cermify

Why this happens

How platforms treat it

PlatformResult
KDPreject
Apple Booksreject
Google Playreject
Kobowarning

How Cermify detects it

  1. Locate toc.ncx (EPUB 2) and/or the nav XHTML (EPUB 3) in the package.
  2. Verify the OPF manifest declares the navigation document with the correct media-type and properties.
  3. Compare nav/NCX targets to real chapter hrefs and fragment ids.
  4. Confirm the spine (or EPUB 3 landmarks) references the same navigation document.

Automatic repair

Cermify can regenerate a basic NCX/nav from the spine and chapter headings when structure is readable, then wire it into the OPF. Custom multi-level marketing TOCs may need manual tuning.

Manual fix

  1. Decide EPUB 2 (NCX) vs EPUB 3 (nav document); KDP accepts both when correctly declared.
  2. Create or repair toc.ncx / nav.xhtml so each entry href exists in the package.
  3. Declare the file in the OPF manifest; set spine toc="ncx" for EPUB 2 or mark the nav with properties="nav".
  4. Rebuild and verify chapter list in Kindle Previewer.

Examples

Navigation must be declared in the package manifest.

Incorrect

<!-- OPF: no NCX/nav item -->
<item id="chap1" href="chapter1.xhtml" media-type="application/xhtml+xml"/>

Correct

<item id="ncx" href="toc.ncx" media-type="application/x-dtbncx+xml"/>
<!-- or EPUB 3: -->
<item id="nav" href="nav.xhtml" media-type="application/xhtml+xml" properties="nav"/>

FAQ

Do I need both NCX and an EPUB 3 nav?

For EPUB 3, the nav document is required. Including a dual NCX is optional for Kindle compatibility; a missing or broken primary nav/NCX is what fails validation.

My in-book HTML TOC looks fine—why still fail?

The HTML contents page is separate from the machine-readable NCX/nav. Kindle uses the nav/NCX for Go To → Table of Contents.

Can auto-repair invent chapter titles?

It derives titles from headings or filenames when possible. If chapters lack headings, review the generated labels before publishing.

Related errors

References