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EPUBCheck · Package document (OPF)

OPF-030

Updated:

EPUBCheck OPF-030 is an error message: “The unique-identifier "…" was not found.” The package element's unique-identifier attribute names an id that no dc:identifier element has.

The official message

The unique-identifier "%1$s" was not found.

Default severity
Error. The EPUB breaks a rule of the specification and is invalid. Stores and Send to Kindle may reject it, and EPUBCheck exits with status 1.
EPUBCheck version
5.4.0

%1$s, %2$s… are filled in with the file, value or element EPUBCheck found.

Typical causes

  • The id on dc:identifier was renamed or removed, for example when editing metadata by hand.

How to fix it

  • Make the id on one dc:identifier match the unique-identifier attribute, for example <package unique-identifier="uid"> with <dc:identifier id="uid">urn:uuid:…</dc:identifier>.

Terms used here

Other OPF messages

  • OPF-029 The file "…" does not appear to match the media type …, as specified in the OPF file.
  • OPF-031 File listed in reference element in guide was not declared in OPF manifest: ….
  • OPF-028 Undeclared prefix: "…".
  • OPF-027 Undefined property: "…".
  • OPF-033 The spine contains no linear resources.
  • OPF-026 Found malformed property value: "…".

Message text and severity from EPUBCheck 5.4.0 (W3C, BSD-3-Clause). Explanation by EPUBLab.

FAQ

What does EPUBCheck OPF-030 mean?

EPUBCheck OPF-030 is an error message: “The unique-identifier "…" was not found.” The package element's unique-identifier attribute names an id that no dc:identifier element has.

Is OPF-030 an error?

OPF-030 is reported as error by default. The EPUB breaks a rule of the specification and is invalid. Stores and Send to Kindle may reject it, and EPUBCheck exits with status 1.