Embedded cover not found or can't be identified

All books have two covers: one that you upload separately to our platform, and one that should be embedded (included) in your EPUB file.

The book cover you upload separately is the one the stores use to display your cover in the store in good quality. This image should have a high resolution, as people often click on the cover and like to see it in full size.

The embedded book cover is the one that is "inside" your book, included in the EPUB file. If someone buys the book, the embedded cover is downloaded with the book, and it will be displayed on the virtual bookshelf of the reader. This image doesn't have to be as large as the one you uploaded separately; actually, the image you are using here cannot be larger than 4 megapixels: 4 million pixels (so a 1600×2400 size works just fine).

Common causes

There might be several reasons why your embedded cover is not accepted upon book upload.

  1. Cover is not embedded / not included in the EPUB file: Please read on :)
  2. The cover is embedded, but it is larger than 4 megapixels: Often a cover that is larger than 4 megapixels (4,000,000 pixels) is not recognized upon upload.
  3. Cover's name has non-supported characters: If your book cover's name has unsupported characters, most often spaces or dashes, e.g. My book cover.jpg, it won't be recognized as embedded cover. If this is the case, simply rename your cover image. For example, cover.jpg would work. Don't forget to make sure that your cover is marked as "cover".

Embed an ebook cover using Sigil or Calibre


Click the big blue + (Add Existing Files) and select the image from your computer.

It will automatically go in the "Images" folder on the left. Right-click the file and set it as the cover image.

Make sure that your picture is not larger than 4 megapixels, and that the name only contains Latin letters or numbers, e.g., cover.jpg.


If you are using Calibre, just open your book in the main Calibre software, then simply right-click your book, and select Edit metadata individually.

Then simply click "Browse" to select the cover.

Make sure that your picture is not larger than 4 megapixels, and that the name only contains Latin letters or numbers, e.g., cover.jpg.

Check the code

If you have tried everything but nothing works, it is possible that something is wrong in the code. Filenames containing non-standard characters like spaces or colons could lead to errors in embedding the cover.

Simply open your book with Sigil or Calibre Ebook Editor, and double click the content.opf file. Please check if it contains the following line (marked with blue):

<metadata xmlns:opf="http://www.idpf.org/2007/opf" xmlns:dc="http://purl.org/dc/elements/1.1/">
<meta content="0.9.8" name="Sigil version" />
<dc:title>Book Title</dc:title>
<dc:date opf:event="modification">2017-09-06</dc:date>
<dc:creator opf:role="aut">Author</dc:creator>
<dc:identifier id="BookId" opf:scheme="UUID"></dc:identifier>
<meta content="cover.jpg" name="cover" />

Simply replace 'cover.jpg' with the name of your own cover file.