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OPF-025Critical Ingestion Error

Property value list "resource" is not allowed, only one value must ...

Property value list "resource" is not allowed, only one value must be specified.

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Fix all OPF-025 errors in your EPUB automatically

PreFlight checks for OPF-025 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 Property value list "resource" is not allowed, only one value must be specified.. 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-025: Property value list "resource" is not allowed, only one value must be specified.

Manual Fix Instructions (for Sigil / Calibre)

  1. Locate the file and line flagged under rule OPF-025 in your EPUB editor (Sigil or Calibre).
  2. Apply the required syntax correction matching the OPF-025 specification.
  3. Re-pack and validate with PreFlight EPUB to confirm zero residual errors.