Back to Error DirectoryW3C EPUBCheck Standard
OPF-002Critical Ingestion Error

The OPF file "resource" was not found in the EPUB.

The OPF file "resource" was not found in the EPUB.

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Fix all OPF-002 errors in your EPUB automatically

PreFlight checks for OPF-002 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 OPF file "resource" was not found in the EPUB.. 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 OPF-002: The OPF file "resource" was not found in the EPUB.

Manual Fix Instructions (for Sigil / Calibre)

  1. Locate the file and line flagged under rule OPF-002 in your EPUB editor (Sigil or Calibre).
  2. Apply the required syntax correction matching the OPF-002 specification.
  3. Re-pack and validate with PreFlight EPUB to confirm zero residual errors.