Back to Error DirectoryW3C EPUBCheck Standard
RSC-014Critical Ingestion Error

Fragment identifier defines an incompatible resource type.

Fragment identifier defines an incompatible resource type.

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Fix all RSC-014 errors in your EPUB automatically

PreFlight checks for RSC-014 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 Fragment identifier defines an incompatible resource type.. 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-014: Fragment identifier defines an incompatible resource type.

Manual Fix Instructions (for Sigil / Calibre)

  1. Locate the file and line flagged under rule RSC-014 in your EPUB editor (Sigil or Calibre).
  2. Apply the required syntax correction matching the RSC-014 specification.
  3. Re-pack and validate with PreFlight EPUB to confirm zero residual errors.