EpubCCEPUBCheck OPF-044: fallback has no XHTML
Updated:
EPUBCheck OPF-044 is an error message: “Spine item with non-standard media-type "…" has no EPUB content document fallback.” A spine item of a non-standard media type has a fallback chain, but no item in that chain is an EPUB content document. EPUB requires every spine fallback chain to end in a document reading apps can always show.
The official message
Spine item with non-standard media-type "%1$s" has no EPUB content document fallback.
- Default severity
- Error. The EPUB breaks a rule of the specification and is invalid. Stores and Send to Kindle may reject it, and EPUBCheck exits with status 1.
- EPUBCheck version
- 5.4.0
%1$s, %2$s… are filled in with the file, value or element EPUBCheck found.
Typical causes
- A fallback that points to another foreign file, such as one image format falling back to another.
- The XHTML fallback at the end of the chain was removed.
- A fallback chain that ends at a file with a mistyped media type.
How to fix it
When it's not this
If the spine item has no fallback attribute at all, that is OPF-043.
Terms used here
Other OPF messages
OPF-043Spine item with non-standard media-type "…" has no fallback.OPF-045Encountered circular reference in fallback chain.OPF-042"…" is not a permissible spine media-type.OPF-041Fallback-style item with id "…" could not be found.OPF-040Fallback item with id "…" could not be found.OPF-048Package 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.