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EPUBCheck · Package document (OPF)

EPUBCheck OPF-043: spine item without fallback

Updated:

EPUBCheck OPF-043 is an error message: “Spine item with non-standard media-type "…" has no fallback.” The spine lists a file that is not an EPUB content document and gives no fallback to one. Reading apps must be able to show every spine item, so a foreign file needs a fallback chain ending in XHTML or SVG.

The official message

Spine item with non-standard media-type "%1$s" has no fallback.

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

  • An image, PDF or other non-XHTML file placed directly in the spine.
  • A spine item whose fallback attribute was removed.
  • A media type typo that makes an XHTML file look like a foreign one.

How to fix it

  1. Read the media type EPUBCheck names; if it is a typo for application/xhtml+xml, fix the manifest.
  2. Otherwise wrap the resource in an XHTML document and put that in the spine.
  3. Or give the item a fallback attribute pointing to a content document with the same content.

When it's not this

If a fallback exists but none of its items is a content document, that is OPF-044.

Terms used here

Other OPF messages

  • OPF-042 "…" is not a permissible spine media-type.
  • OPF-044 Spine item with non-standard media-type "…" has no EPUB content document fallback.
  • OPF-041 Fallback-style item with id "…" could not be found.
  • OPF-045 Encountered circular reference in fallback chain.
  • OPF-040 Fallback item with id "…" could not be found.
  • OPF-048 Package tag is missing its required unique-identifier attribute and value.

Sources

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

FAQ

What does EPUBCheck OPF-043 mean?

EPUBCheck OPF-043 is an error message: “Spine item with non-standard media-type "…" has no fallback.” The spine lists a file that is not an EPUB content document and gives no fallback to one. Reading apps must be able to show every spine item, so a foreign file needs a fallback chain ending in XHTML or SVG.

Is OPF-043 an error?

OPF-043 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.