Cermify · Error Library · KDP

Metadata · E-OPF

Missing required metadata (title, language, identifier)

Your package file (OPF) is missing required metadata KDP expects: title, language, or a unique identifier.

Severity
error
Automatic repair
Supported
Submission impact
KDP: reject
Rule ID
E-OPF
Error: Missing required metadata (title, language, identifier)
Category: Metadata
Severity: error
Auto Repair: Supported
Rule ID: E-OPF
Affected: KDP=reject, Apple=reject, Google=reject, Kobo=reject
Check this automatically with Cermify

Why this happens

How platforms treat it

PlatformResult
KDPreject
Apple Booksreject
Google Playreject
Koboreject

How Cermify detects it

  1. Open the OPF package document and read the metadata section.
  2. Require non-empty dc:title, dc:language, and dc:identifier.
  3. Verify package unique-identifier references an existing identifier id.
  4. Optionally note missing recommended fields (creator, date) as guidance only.

Automatic repair

Cermify can insert placeholder or inferred title/language/identifier when safe defaults are available (filename, locale, generated UUID). Review title and ISBN/UUID before publishing.

Manual fix

  1. Add <dc:title> with the storefront title.
  2. Add <dc:language> using a BCP 47 tag (e.g. en, en-US, zh-CN).
  3. Add <dc:identifier id="bookid">…</dc:identifier> and set unique-identifier="bookid" on <package>.
  4. Save, repackage, and confirm metadata in epubcheck and KDP.

Examples

Title, language, and identifier are required package metadata.

Incorrect

<metadata>
  <dc:creator>A. Author</dc:creator>
</metadata>

Correct

<package unique-identifier="bookid" ...>
  <metadata>
    <dc:identifier id="bookid">urn:uuid:12345678-1234-1234-1234-123456789abc</dc:identifier>
    <dc:title>Sample Title</dc:title>
    <dc:language>en</dc:language>
  </metadata>
</package>

FAQ

Must the identifier be an ISBN?

No. A UUID URN is valid for EPUB. Use your ISBN when you have one assigned for the ebook edition.

Does KDP overwrite my OPF title?

KDP storefront metadata can differ, but the EPUB still needs valid package metadata to pass validation.

Is creator required for this rule?

E-OPF focuses on title, language, and identifier. Author/creator is strongly recommended but not the core fail for this rule id.

Related errors

References