PKG-014 is reported as warning by default. The EPUB is still valid, but something is likely to cause problems in some reading apps. EPUBCheck exits with 0 unless you pass --failonwarnings.

EPUBCheck · Package and ZIP container

`PKG-014`

Updated: Nov 3, 2026

EPUBCheck PKG-014 is a warning message: “The EPUB contains empty directory "…".” The EPUB archive contains an empty folder, which serves no purpose and is reported so you can remove it.

The official message

The EPUB contains empty directory "%1$s".

Default severity: Warning. The EPUB is still valid, but something is likely to cause problems in some reading apps. EPUBCheck exits with 0 unless you pass --failonwarnings.
EPUBCheck version: 5.4.0

%1$s, %2$s… are filled in with the file, value or element EPUBCheck found.

Typical causes

A folder left behind after moving or deleting files while editing the book.

How to fix it

Delete the empty folder from the book's source and rebuild the archive.
Rebuild the archive with the mimetype file first and stored uncompressed, for example from the folder that contains the book: zip -X0 book.epub mimetype and then zip -rX9 book.epub META-INF OEBPS (use your own folder names).

Terms used here

What is the EPUB container (OCF)?

Other PKG messages

PKG-012 The file name "…" contains non-ASCII characters, which might create interoperability issues with older reading systems.
PKG-016 Use only lowercase characters for the EPUB file extension for maximum compatibility.
PKG-011 The file name "…" is not allowed to end with ".".
PKG-017 Uncommon EPUB file extension.
PKG-010 The file name "…" contains spaces, which may create interoperability issues with older reading systems.
PKG-009 The file name "…" contains characters that are not allowed in OCF file names: ….

Message text and severity from EPUBCheck 5.4.0 (W3C, BSD-3-Clause). Explanation by EPUBLab.