# EPUBCheck OPF-034: The spine contains multiple references…

Source: https://epublab.com/epubcheck/opf-034/ (updated 2026-11-03)

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; each document may appear only once.

- Official message (EPUBCheck 5.4.0): The spine contains multiple references to the manifest item with id "%1$s".
- Default severity: Error

## Typical causes

- A chapter added twice by a tool or by hand, often when merging books.

## How to fix it

- Delete the duplicate itemref from the spine.

Message text and severity: EPUBCheck (W3C, BSD-3-Clause). Explanation: EPUBLab.