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EPUBCheck · Navigation document

EPUBCheck NAV-001: nav document in EPUB 2

Updated:

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.

The official message

The nav file is not supported for EPUB v2.

Default severity
Error. The EPUB breaks a rule of the specification and is invalid. Stores and Send to Kindle may reject it, and EPUBCheck exits with status 1.
EPUBCheck version
5.4.0

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.

Terms used here

Other NAV messages

  • NAV-003 The Navigation Document must have a page list when content document(s) contain page breaks (epub:type="pagebreak").
  • NAV-006 Content documents contain "figure" elements but the Navigation Document does not have a listing of figures (epub:type="loi").
  • NAV-010 "…" nav must not link to remote resources; found link to "…".
  • NAV-011 "…" nav must be in reading order; link target "…" is before the previous link’s target in … order.

Sources

Message text and severity from EPUBCheck 5.4.0 (W3C, BSD-3-Clause). Explanation by EpubCC.

FAQ

What does EPUBCheck NAV-001 mean?

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.

Is NAV-001 an error?

NAV-001 is reported as error by default. The EPUB breaks a rule of the specification and is invalid. Stores and Send to Kindle may reject it, and EPUBCheck exits with status 1.