Back to Error DirectoryW3C EPUBCheck Standard
NAV-001Retailer Warning

The nav file is not supported for EPUB v2.

The nav file is not supported for EPUB v2.

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Fix all NAV-001 errors in your EPUB automatically

PreFlight checks for NAV-001 issues in memory and provides 1-click remediation during client-side packaging.

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What This Error Means in Plain English

EPUBCheck detected The nav file is not supported for EPUB v2.. Digital reading systems and bookstores require standard conformance to ensure compatibility across all reading apps.

Why Retailers & EAA Regulations Block This File

Automated book distributors (Apple Books, Amazon KDP, Kobo, and IngramSpark) run strict EPUBCheck validation on ingest and reject non-compliant files.

Technical Specification: W3C EPUBCheck rule NAV-001: The nav file is not supported for EPUB v2.

Manual Fix Instructions (for Sigil / Calibre)

  1. Locate the file and line flagged under rule NAV-001 in your EPUB editor (Sigil or Calibre).
  2. Apply the required syntax correction matching the NAV-001 specification.
  3. Re-pack and validate with PreFlight EPUB to confirm zero residual errors.