Knowledge · Rule
Incorrect or missing mimetype / manifest entries
Package Structure · E-MIME
Definition
Your EPUB's mimetype file or manifest doesn't correctly declare all the files inside the package, which is a hard requirement for EPUB validity.
Why
- mimetype file missing, wrong content, or compressed / not stored first in the zip.
- Files present in the zip but absent from the OPF manifest.
- Manifest hrefs pointing at paths that are not in the package.
- Wrong media-type for an item (e.g. XHTML declared as plain text).
Impact
May block submission on KDP when this rule fails.
Platforms
| Platform | Result |
|---|---|
| KDP | May reject |
| Apple Books | May reject |
| Google Play | May reject |
| Kobo | May reject |
References
- EPUB OCF — mimetype
- EPUB manifest
- Cermify Rule Set kdp-epub-2026-07
Last updated · 2026-08-03
Why we believe
Provenance is loaded from RID (same source as Rule Radar) — not a second copy.
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