# EPUBCheck PKG-026: Obfuscated resource must be a Font Core…

Source: https://epublab.com/epubcheck/pkg-026/ (updated 2026-11-03)

EPUBCheck PKG-026 is an error message: “Obfuscated resource must be a Font Core Media Type (was declared as "…" in "…").” A file that is not a font is listed as obfuscated in META-INF/encryption.xml; font obfuscation only applies to font files.

- Official message (EPUBCheck 5.4.0): Obfuscated resource must be a Font Core Media Type (was declared as "%1$s" in "%2$s").
- Default severity: Error

## Typical causes

- An encryption.xml copied from another book that lists files this book does not use as fonts.
- A tool that obfuscated every resource instead of only the fonts.

## How to fix it

- Remove the entry for the non-font file from META-INF/encryption.xml and store that file unobfuscated.

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