# EPUBCheck OPF-029: file is not its media type, how to fix it

Source: https://epubcc.com/epubcheck/opf-029/ (updated 2026-11-04)

EPUBCheck OPF-029 is an error message: “The file "…" does not appear to match the media type …, as specified in the OPF file.” A file's content does not match the media type declared for it in the manifest. EPUBCheck looks at the file itself, so a wrong declaration can make reading apps try to decode it in the wrong format.

- Official message (EPUBCheck 5.4.0): The file "%1$s" does not appear to match the media type %2$s, as specified in the OPF file.
- Default severity: Error

## Typical causes

- A PNG declared as image/jpeg, or the reverse.
- A file converted to another format without updating the manifest.
- A file renamed with a new extension without being converted.

## How to fix it

1. Check the real format of the file EPUBCheck names (an image editor or the file command will tell you).
2. Change the manifest media-type to that real format.
3. Or convert the file to the format the manifest declares, keeping its name and references consistent.

## When it's not this

If only the extension disagrees with the format, EPUBCheck reports PKG-022.

## Sources

- EPUB 3.3, §5.6.2 The item element: https://www.w3.org/TR/epub-33/#sec-item-elem (read 2026-11-04)
- EPUB 3.3, §3.2 Core media types: https://www.w3.org/TR/epub-33/#sec-core-media-types (read 2026-11-04)

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