# EPUBCheck OPF-043: Spine item with non-standard media-type…

Source: https://epublab.com/epubcheck/opf-043/ (updated 2026-11-03)

EPUBCheck OPF-043 is an error message: “Spine item with non-standard media-type "…" has no fallback.” The spine lists a file that is not an EPUB content document and gives no fallback to one.

- Official message (EPUBCheck 5.4.0): Spine item with non-standard media-type "%1$s" has no fallback.
- Default severity: Error

## Typical causes

- An image, PDF or other non-XHTML file placed directly in the spine.

## How to fix it

- Wrap the resource in an XHTML document and put that in the spine, or give the item a fallback to a content document.

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