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RSC-005Critical Ingestion Error

Missing Required Attribute 'alt' on img Tag

An image tag in an XHTML chapter is missing an alt attribute.

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Fix all RSC-005 errors in your EPUB automatically

PreFlight parses every chapter's DOM tree, locates all alt-less image elements, and automatically assigns compliant descriptive or decorative alt="" attributes in memory.

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What This Error Means in Plain English

Every single image inside your book must tell a screen reader what it represents. When an img tag lacks an alt attribute, visually impaired readers hit an unreadable blockage, causing automated rejection by Apple Books and IngramSpark.

Why Retailers & EAA Regulations Block This File

Strictly mandated by the European Accessibility Act (EAA) and EPUB 3.3 specification. Books missing alt attributes fail automated ingestion tests immediately.

Technical Specification: Occurs during XHTML validation when the XML parser encounters an <img> element without an alt attribute. In EPUB 3, even decorative images require an empty alt="" attribute to pass conformance.

XML Structure Comparison

Non-Compliant / Rejected
<img src="../images/chapter-header.png" />
Compliant / Accepted
<img src="../images/chapter-header.png" alt="Decorative chapter ornament" role="presentation" />

Manual Fix Instructions (for Sigil / Calibre)

  1. Open the flagged .xhtml chapter inside Sigil or Calibre Editor.
  2. Search for <img src="..."> elements without an alt attribute.
  3. Add alt="Description of image" or alt="" if the image is purely decorative.
  4. Re-validate with epubcheck to confirm resolution.