Back to Error DirectoryW3C EPUBCheck Standard
MED-003Retailer Warning

Picture "img" elements must reference core media type resources, bu...

Picture "img" elements must reference core media type resources, but found resource "resource" of type "resource".

Automated 1-Click Fix Ready

Fix all MED-003 errors in your EPUB automatically

PreFlight checks for MED-003 issues in memory and provides 1-click remediation during client-side packaging.

Scan & Fix Now

What This Error Means in Plain English

EPUBCheck detected Picture "img" elements must reference core media type resources, but found resource "resource" of type "resource".. 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-003: Picture "img" elements must reference core media type resources, but found resource "resource" of type "resource".

Manual Fix Instructions (for Sigil / Calibre)

  1. Locate the file and line flagged under rule MED-003 in your EPUB editor (Sigil or Calibre).
  2. Apply the required syntax correction matching the MED-003 specification.
  3. Re-pack and validate with PreFlight EPUB to confirm zero residual errors.