# EPUBCheck PKG-012: The file name … contains non-ASCII…

Source: https://epublab.com/epubcheck/pkg-012/ (updated 2026-11-03)

EPUBCheck PKG-012 is a usage message: “The file name "…" contains non-ASCII characters, which might create interoperability issues with older reading systems.” A file name inside the EPUB contains non-ASCII characters (accents, other scripts), which is valid but may break older reading systems.

- Official message (EPUBCheck 5.4.0): The file name "%1$s" contains non-ASCII characters, which might create interoperability issues with older reading systems.
- Default severity: Usage

## Typical causes

- Files named after titles in languages other than English, such as "capítulo-1.xhtml".

## How to fix it

- If you target older devices, rename the file with ASCII characters only.
- After renaming, update every reference to the file: the manifest in the package document, links and image sources in the XHTML, and url() references in the CSS.

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