Back to Error DirectoryW3C EPUBCheck Standard
RSC-021Critical Ingestion Error

A Search Key Map Document must point to Content Documents ("resourc...

A Search Key Map Document must point to Content Documents ("resource" was not found in the spine).

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What This Error Means in Plain English

EPUBCheck detected A Search Key Map Document must point to Content Documents ("resource" was not found in the spine).. 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 RSC-021: A Search Key Map Document must point to Content Documents ("resource" was not found in the spine).

Manual Fix Instructions (for Sigil / Calibre)

  1. Locate the file and line flagged under rule RSC-021 in your EPUB editor (Sigil or Calibre).
  2. Apply the required syntax correction matching the RSC-021 specification.
  3. Re-pack and validate with PreFlight EPUB to confirm zero residual errors.