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OPF-018bCritical Ingestion Error

The "remote-resources" property was declared in the Package Documen...

The "remote-resources" property was declared in the Package Document, but no reference to remote resources has been found; please check scripted content to make sure the property is legit.

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PreFlight checks for OPF-018b 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 "remote-resources" property was declared in the Package Document, but no reference to remote resources has been found; please check scripted content to make sure the property is legit.. 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-018b: The "remote-resources" property was declared in the Package Document, but no reference to remote resources has been found; please check scripted content to make sure the property is legit.

Manual Fix Instructions (for Sigil / Calibre)

  1. Locate the file and line flagged under rule OPF-018b in your EPUB editor (Sigil or Calibre).
  2. Apply the required syntax correction matching the OPF-018b specification.
  3. Re-pack and validate with PreFlight EPUB to confirm zero residual errors.