# EPUBCheck RSC-004: encrypted file not checked, how to fix it

Source: https://epubcc.com/epubcheck/rsc-004/ (updated 2026-11-04)

EPUBCheck RSC-004 is an info message: “File "…" is encrypted, its content will not be checked.” A file is encrypted (listed in META-INF/encryption.xml), so EPUBCheck cannot read it and skips its checks. It is an informative message, not an error.

- Official message (EPUBCheck 5.4.0): File "%1$s" is encrypted, its content will not be checked.
- Default severity: Info

## Typical causes

- Books protected with DRM, where content files are encrypted with a method EPUBCheck cannot read.
- A store or distributor copy of the book rather than the original file.

## How to fix it

1. Nothing to fix if the encryption is intended.
2. To check the content, validate the unencrypted source EPUB you produced, before DRM was applied.
3. Never try to remove DRM from a book you do not have the right to modify.

## When it's not this

Font obfuscation listed for a non-font file is a different problem, PKG-026.

## Sources

- EPUB 3.3, §4.2.6.3.2 Encryption file (encryption.xml): https://www.w3.org/TR/epub-33/#sec-container-metainf-encryption.xml (read 2026-11-04)

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