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.