Back to Error DirectoryW3C EPUBCheck Standard
OPF-018Critical 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.

Automated 1-Click Fix Ready

Fix all OPF-018 errors in your EPUB automatically

PreFlight checks for OPF-018 issues in memory and provides 1-click remediation during client-side packaging.

Scan & Fix Now

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.. 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-018: The "remote-resources" property was declared in the Package Document, but no reference to remote resources has been found.

Manual Fix Instructions (for Sigil / Calibre)

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