Back to Error DirectoryW3C EPUBCheck Standard
NAV-004Retailer Warning

The Navigation Document should contain the full document heading hi...

The Navigation Document should contain the full document heading hierarchy in EDUPUB.

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PreFlight checks for NAV-004 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 Navigation Document should contain the full document heading hierarchy in EDUPUB.. 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-004: The Navigation Document should contain the full document heading hierarchy in EDUPUB.

Manual Fix Instructions (for Sigil / Calibre)

  1. Locate the file and line flagged under rule NAV-004 in your EPUB editor (Sigil or Calibre).
  2. Apply the required syntax correction matching the NAV-004 specification.
  3. Re-pack and validate with PreFlight EPUB to confirm zero residual errors.