Why your Table of Contents breaks on older Kindles vs the iPad app (NCX vs HTML)

A fractured table of contents is a common issue in indie ebooks, where chapter links work on some devices but fail on older e-ink Kindles. The problem arises when authors or auto-converters only build an HTML table of contents, which looks fine but doesn’t work for older e-readers. These older devices rely on a hidden backend map called an NCX file. If the export software doesn’t program the .ncx file or the newer EPUB3 Navigation Document, the Kindle won’t know how to skip chapters. Authors can use a free editor like Sigil to ensure both the HTML and NCX navigational maps are synced. A fractured TOC can lead to automated formatting complaints from KDP. Running the file through EpubCheck will flag a missing nav document.

Most authors (or auto-converters) just build an HTML table of contents at the front of the book and hyper-link the text to the chapters.
Older e-readers don’t use the visual text to navigate. They rely on a hidden backend map called an NCX file ( toc.ncx )
If your export software only builds the visual HTML list and fails to program the .ncx file or the newer EPUB3 Navigation Document ( nav.xhtml ), the physical hardware buttons on a Kindle won’t know how to skip chapters.

📚 BookAddict’s Take: KDP authors should consider using Sigil or EpubCheck to avoid formatting errors and ensure their ebooks work across different generations of devices.

Source: Reddit r/selfpublish |
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