# EPUBCheck OPF-040: Fallback item with id … could not be…

Source: https://epublab.com/epubcheck/opf-040/ (updated 2026-11-03)

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.

- Official message (EPUBCheck 5.4.0): Fallback item with id "%1$s" could not be found.
- Default severity: Error

## Typical causes

- The fallback item was removed or its id renamed.

## How to fix it

- Point the fallback at an existing item id, or remove the fallback if the resource is a core media type and needs none.

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