# EPUBCheck NAV-001: nav document in EPUB 2, how to fix it

Source: https://epubcc.com/epubcheck/nav-001/ (updated 2026-11-04)

EPUBCheck NAV-001 is an error message: “The nav file is not supported for EPUB v2.” An EPUB 2 publication includes an EPUB 3 navigation document, which EPUB 2 does not support. EPUBCheck validates the book by the version declared in the package document, and in version 2.0 the table of contents is the NCX.

- Official message (EPUBCheck 5.4.0): The nav file is not supported for EPUB v2.
- Default severity: Error

## Typical causes

- A package with version="2.0" that contains a nav document, often after a partial conversion to EPUB 3.
- A nav document added by an editor to an old EPUB 2 book.

## How to fix it

1. Decide which version the book should be. EPUB 3 is the current one.
2. To upgrade, set version="3.0" on the package element, add the required metadata such as dcterms:modified, and give the nav item properties="nav" in the manifest.
3. To stay on EPUB 2, remove the nav document and keep the NCX.
4. Rebuild the EPUB and run EPUBCheck again to confirm the message is gone.

## When it's not this

If the book is EPUB 3 and the nav has problems of its own, see NAV-010 or NAV-011.

## Sources

- EPUB 3.3, §7 EPUB navigation document: https://www.w3.org/TR/epub-33/#sec-nav (read 2026-11-04)
- EPUB 3.3, §5.9.5 NCX: https://www.w3.org/TR/epub-33/#sec-opf2-ncx (read 2026-11-04)

Message text and severity: EPUBCheck (W3C, BSD-3-Clause). Explanation: EpubCC.