# EPUBCheck OPF-035: Media type text/html is not appropriate…

Source: https://epublab.com/epubcheck/opf-035/ (updated 2026-11-03)

EPUBCheck OPF-035 is a warning message: “Media type "text/html" is not appropriate for XHTML/OPS.” A content document is declared as text/html; EPUB content documents are XHTML and need application/xhtml+xml.

- Official message (EPUBCheck 5.4.0): Media type "text/html" is not appropriate for XHTML/OPS.
- Default severity: Warning
- EPUBCheck's suggestion: Use "application/xhtml+xml" instead.

## Typical causes

- Manifests generated by tools that treat chapters as web pages.

## How to fix it

- Change the media-type of those items to application/xhtml+xml, and make sure the files are well-formed XHTML.

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