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EPUBCheck · Package document (OPF)

EPUBCheck OPF-041: fallback-style not found

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EPUBCheck OPF-041 is an error message: “Fallback-style item with id "…" could not be found.” An EPUB 2 manifest item's fallback-style attribute names an id that no manifest item has. In EPUB 2, fallback-style points to a stylesheet to use with a non-standard document, so a missing target breaks it.

The official message

Fallback-style 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 stylesheet item was removed or its id renamed.
  • A typo in the fallback-style attribute.
  • An attribute copied from another book.

How to fix it

  1. Read the id EPUBCheck names.
  2. Point fallback-style at an existing CSS item, or add the missing stylesheet to the manifest.
  3. Remove the attribute if the document does not need a fallback style.

When it's not this

If it is the plain fallback attribute that points nowhere, that is OPF-040.

Terms used here

Other OPF messages

  • OPF-040 Fallback item with id "…" could not be found.
  • OPF-042 "…" is not a permissible spine media-type.
  • OPF-043 Spine item with non-standard media-type "…" has no fallback.
  • OPF-044 Spine item with non-standard media-type "…" has no EPUB content document fallback.
  • OPF-037 Found deprecated media-type "…".
  • OPF-045 Encountered circular reference in fallback chain.

Sources

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

FAQ

What does EPUBCheck OPF-041 mean?

EPUBCheck OPF-041 is an error message: “Fallback-style item with id "…" could not be found.” An EPUB 2 manifest item's fallback-style attribute names an id that no manifest item has. In EPUB 2, fallback-style points to a stylesheet to use with a non-standard document, so a missing target breaks it.

Is OPF-041 an error?

OPF-041 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.