Back to Error DirectoryW3C EPUBCheck Standard
NCX-006Critical Ingestion Error

Empty "text" label in the NCX document

Empty "text" label in the NCX document

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Fix all NCX-006 errors in your EPUB automatically

PreFlight checks for NCX-006 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 Empty "text" label in the NCX document. 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 NCX-006: Empty "text" label in the NCX document

Manual Fix Instructions (for Sigil / Calibre)

  1. Locate the file and line flagged under rule NCX-006 in your EPUB editor (Sigil or Calibre).
  2. Apply the required syntax correction matching the NCX-006 specification.
  3. Re-pack and validate with PreFlight EPUB to confirm zero residual errors.