Unfortunately this error message can have many possible causes:

• You may be receiving this message if you are attempting to download a book you have already downloaded to your bookshelf. Please check the app bookshelf under "Books on this device" to see if the ebook was already downloaded.
• You may be receiving this error message if there is not enough space on your device to store the ebook. Ebooks can vary wildly in size from under a megabyte to around a gigabyte in size. Also the PDF format can be much larger than the EPUB format. If you are unsure if you have enough space, please try downloading the ebook on your computer and you can check the file size. or contact our support team. We can check the file size for you.
• You may be receiving this error because there is an account mismatch and you are attempting to download an ebook that isn't in your account. Please follow the steps in this help article to rule this out.

The remaining possible issues are either due to an ebook file issue, or an app issue. If you get this fair without resolving the issue please contact our support team. Confirm the ebook you are experiencing the issue with and the format you wish to download. Please also quote this help article and let us know you have already tried the previously suggested solutions. We will then check the ebook file for errors. If any issues are found we will contact the publisher to request a replacement file. If the file isn't at fault it may be an app error. In which case you should try uninstalling the app and reinstalling before retrying the download again.