# EPUBCheck OPF-013: Resource … is declared with MIME type …

Source: https://epublab.com/epubcheck/opf-013/ (updated 2026-11-03)

EPUBCheck OPF-013 is a warning message: “Resource "…" is declared with MIME type "…" in content, but has MIME type "…" in the package document.” A content document declares one media type for a resource (in a type attribute) and the manifest declares another.

- Official message (EPUBCheck 5.4.0): Resource "%1$s" is declared with MIME type "%2$s" in content, but has MIME type "%3$s" in the package document.
- Default severity: Warning

## Typical causes

- An object, embed, link or source element whose type attribute disagrees with the manifest item.

## How to fix it

- Make the type attribute and the manifest media-type the same, using the file's real format.

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