EpubCCEPUBCheck OPF-040: fallback item not found
Updated:
EPUBCheck OPF-040 is an error message: “Fallback item with id "…" could not be found.” A manifest item's fallback attribute names an id that no manifest item has. Fallbacks let a reading app switch to another format it can render, so a broken fallback chain can leave content unreadable.
The official message
Fallback item with id "%1$s" could not be found.
- Default severity
- Error. The EPUB breaks a rule of the specification and is invalid. Stores and Send to Kindle may reject it, and EPUBCheck exits with status 1.
- EPUBCheck version
- 5.4.0
%1$s, %2$s… are filled in with the file, value or element EPUBCheck found.
Typical causes
- The fallback item was removed or its id renamed.
- A typo in the fallback attribute.
- A fallback copied from another book's manifest.
How to fix it
- Read the id EPUBCheck names.
- Point the fallback at an existing item id, or add the missing item.
- Remove the fallback if the resource is a core media type and needs none.
When it's not this
If the fallback chain loops back on itself, that is OPF-045.
Terms used here
Other OPF messages
OPF-041Fallback-style item with id "…" could not be found.OPF-042"…" is not a permissible spine media-type.OPF-037Found deprecated media-type "…".OPF-043Spine item with non-standard media-type "…" has no fallback.OPF-036Video type "…" might not be supported by reading systemsOPF-044Spine item with non-standard media-type "…" has no EPUB content document fallback.
Sources
Message text and severity from EPUBCheck 5.4.0 (W3C, BSD-3-Clause). Explanation by EpubCC.