# EPUBCheck NAV-001: The nav file is not supported for EPUB v2

Source: https://epublab.com/epubcheck/nav-001/ (updated 2026-11-03)

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.

- 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 partial conversion to EPUB 3.

## How to fix it

- Upgrade the whole package to EPUB 3 (version="3.0" and the required metadata), or remove the nav document and keep the NCX.

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