OPF-034 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.

EPUBCheck · Package document (OPF)

EPUBCheck OPF-034: document twice in spine

Updated: Nov 4, 2026

EPUBCheck OPF-034 is an error message: “The spine contains multiple references to the manifest item with id "…".” The spine lists the same manifest item more than once. EPUB allows each document to appear only once in the reading order, so a duplicate makes the book invalid.

The official message

The spine contains multiple references to the manifest item with id "%1$s".

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 chapter added twice by a tool or by hand.
Books merged from several sources, where the same file ended up in the spine twice.
A copy-paste of an itemref line that was never changed.

How to fix it

Find the id EPUBCheck names in the spine.
Delete the duplicate itemref, keeping the one in the right reading position.
If you really need the same content twice, make a copy of the file with its own manifest item.

When it's not this

If the same file is declared by two manifest items, that is OPF-074.

Terms used here

Other OPF messages

OPF-033 The spine contains no linear resources.
OPF-035 Media type "text/html" is not appropriate for XHTML/OPS.
OPF-032 Guide references "…" which is not a valid "OPS Content Document".
OPF-036 Video type "…" might not be supported by reading systems
OPF-031 File listed in reference element in guide was not declared in OPF manifest: ….
OPF-037 Found deprecated media-type "…".

Sources

EPUB 3.3, §5.7.2 The itemref element · read Nov 4, 2026

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