What is EPUB validation and how do I fix EPUB errors?

EPUB validation (EPUBCheck) confirms your file meets the standard stores require. Chiify validates and auto-heals on upload; here's how to clear errors.

Last updated 2026-06-15

EPUB validation checks that your ebook file meets the official EPUB standard — the thing every store relies on. Chiify runs the industry tool EPUBCheck on your file automatically.

What Chiify does for you

Runs EPUBCheck on upload.
Auto-heals many common problems (mimetype order, broken internal links, remote resources).
Upgrades EPUB 2 to EPUB 3 during delivery so older files still meet store requirements.

Reading the result

Pass — perfect, nothing to do.
Warnings — usually harmless; most stores accept the book anyway.
Errors — these can block acceptance and need a fix.

Fixing errors

The most reliable fix is to upload your DOCX and let Chiify build a clean EPUB 3 from scratch. For specific messages, see common EPUB upload errors.

Validation exists to stop your book from silently failing at a retailer — passing it means smooth sailing into the stores.

Still need help? Open a ticket from your dashboard or email [email protected] — a real person replies.

How do I upload an audiobook to Chiify?

Upload your chapter audio files (MP3 or M4A), a cover, and metadata; Chiify reviews and distributes to audiobook stores. Here's the full process.

Why does my EPUB need a clickable table of contents?

Stores require a clickable navigation TOC so readers can jump between chapters. Chiify builds one automatically when you use heading styles in your DOCX.

Can I schedule a pre-order or set a release date?

Yes — you can schedule a future release so stores list your book for pre-order and launch it automatically on the day. Here's how to plan it.

What's the recommended order of pages inside a book?

Front matter (title, copyright, dedication), then the body, then back matter (about the author, also-by). A clean order helps reviews and reader experience.

What is a copyright page and do I need one?

A copyright page states who owns the book and the year. It's standard, quick to add, and signals professionalism to stores and readers. Here's what to include.