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EPUBCheck · Package document (OPF)

OPF-093

Updated:

EPUBCheck OPF-093 is an error message: “The "media-type" attribute is required for linked resources located in the EPUB container.” A link element in the metadata points to a file inside the EPUB but has no media-type attribute.

The official message

The "media-type" attribute is required for linked resources located in the EPUB container

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

Typical causes

  • A metadata link to a local record or file written without media-type.

How to fix it

  • Add media-type with the linked file's format.

Terms used here

Other OPF messages

  • OPF-092 Language tag "…" is not well-formed: …
  • OPF-091 The item href URL must not have a fragment identifier.
  • OPF-090 It is encouraged to use MIME media type "…" instead of "…".
  • OPF-096 Non-linear content must be reachable, but found no hyperlink to "…".
  • OPF-097 Resource "…" is listed in the manifest, but no reference to it was found in content documents.
  • OPF-088 Unrecognized epub:type value "…".

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

FAQ

What does EPUBCheck OPF-093 mean?

EPUBCheck OPF-093 is an error message: “The "media-type" attribute is required for linked resources located in the EPUB container.” A link element in the metadata points to a file inside the EPUB but has no media-type attribute.

Is OPF-093 an error?

OPF-093 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.