Cermify · Error Library · KDP

Fonts · E-FONT

Font file not declared in manifest

A font file exists in your EPUB but isn't listed in the manifest, so it may not load correctly.

Severity
warning
Automatic repair
Supported
Submission impact
KDP: warning
Rule ID
E-FONT
Error: Font file not declared in manifest
Category: Fonts
Severity: warning
Auto Repair: Supported
Rule ID: E-FONT
Affected: KDP=warning, Apple=warning, Google=warning, Kobo=pass
Check this automatically with Cermify

Why this happens

How platforms treat it

PlatformResult
KDPwarning
Apple Bookswarning
Google Playwarning
Kobopass

How Cermify detects it

  1. Find font binaries (.ttf, .otf, .woff, .woff2) in the package.
  2. Parse @font-face src URLs in CSS.
  3. Ensure each font file is listed in the OPF manifest with an appropriate media-type.
  4. Flag undeclared fonts as E-FONT.

Automatic repair

Cermify can add manifest entries for undeclared font files with standard media-types. Licensing and embedding permissions remain the publisher's responsibility.

Manual fix

  1. Confirm you have redistribution rights for each embedded font.
  2. Add <item> rows for every font file with the correct media-type.
  3. Align @font-face urls with those hrefs.
  4. Recheck on device—fallback fonts may hide undeclared embeds until tested.

Examples

Embedded fonts must be declared in the package manifest.

Incorrect

/* fonts/Literata.ttf present on disk, missing from OPF */
@font-face {
  font-family: "Literata";
  src: url("../fonts/Literata.ttf");
}

Correct

<item id="font-literata" href="fonts/Literata.ttf" media-type="font/ttf"/>
@font-face {
  font-family: "Literata";
  src: url("../fonts/Literata.ttf");
}

FAQ

Is undeclared font always a reject?

Often a warning; the reader may fall back to a system font. Declare fonts for predictable typography and cleaner validation.

Do I need fonts for KDP?

No. Many books rely on device fonts. Embed only when branding requires it and licenses allow.

WOFF2 vs TTF?

Both can work when declared correctly; follow Kindle guidelines for preferred formats in your workflow.

Related errors

References