Back to Error DirectoryW3C EPUBCheck Standard
MED-016Retailer Warning

Media Overlays total duration should be the sum of the durations of...

Media Overlays total duration should be the sum of the durations of all Media Overlays documents.

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PreFlight checks for MED-016 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 Media Overlays total duration should be the sum of the durations of all Media Overlays documents.. 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 MED-016: Media Overlays total duration should be the sum of the durations of all Media Overlays documents.

Manual Fix Instructions (for Sigil / Calibre)

  1. Locate the file and line flagged under rule MED-016 in your EPUB editor (Sigil or Calibre).
  2. Apply the required syntax correction matching the MED-016 specification.
  3. Re-pack and validate with PreFlight EPUB to confirm zero residual errors.