Symptom: You delivered your EPUB via FTP, our Publisher Portal, or API, but your book is failing to process and go live. Our support team may have directed you to this article to resolve an "explicit directory" or "META-INF" issue.
Why is this happening?
The issue comes down to how your EPUB file was packaged. An EPUB is essentially a standard ZIP archive with its file extension changed to .epub.
Professional EPUB creation tools package these files using strict industry standards. However, if an EPUB is zipped manually (e.g., highlighting files on your computer, right-clicking, and selecting "Compress to ZIP"), the operating system creates what are known as "explicit directory entries." This means it creates empty, standalone folder nodes inside the archive for directories like META-INF and OEBPS. Our ingestion system requires strict, standard EPUB formatting and will fail to process files containing these manually created, empty folder nodes.
How to check if your EPUB has this issue
You can check if your EPUB is packaged incorrectly without needing to extract it.
For Windows Users:
- Open the Command Prompt (Press the Windows Key, type cmd, and press Enter).
- Type tar -tvf (make sure to include the space at the end).
- Drag and drop your .epub file directly into the Command Prompt window to auto-fill the file path, and press Enter.
- What to look for: Look at the output list. If you see standalone entries for META-INF/ or OEBPS/ with a file size of 0, your file has explicit directories and will fail.
For Mac/Linux Users:
- Open the Terminal.
- Type unzip -l (include the space).
- Drag and drop your .epub file into the Terminal window and press Enter.
- What to look for: Look at the "Length" and "Name" columns. If you see a META-INF/ folder with a length of 0, your file will fail to process.
How to fix your EPUB
You do not need to be a developer to fix this! You simply need to run your book through an industry-standard EPUB editor to rebuild the file structure correctly.
General Step-by-Step Instructions:
- Open your EPUB: Import or open your failing EPUB file into a dedicated EPUB editing software.
- Force a Rebuild: To force the software to repackage the book, make a tiny, invisible change. Open any text or HTML file within the editor, delete a single letter or space, and type it exactly back in.
- Save and Export: Save your project and export it as a new EPUB file. This action typically rebuilds the EPUB using strict industry standards, automatically stripping out the hidden, problematic folders.