This error message indicates that you are trying to open a book that was already downloaded to another Adobe ID under the current download period.

The most common reason for receiving this message is if you initially downloaded the book to Adobe Digital Editions without authorizing it to an Adobe ID (see Download, full document: An Adobe ID - what it's needed for and how to get one), and then either try to download or transfer it to another device, or try to authorize ADE to an Adobe ID after the book has been downloaded.

When you authorize ADE without an Adobe ID, it's associating any downloads with that anonymous activation. If you later decide to authorize ADE to your Adobe ID, you will be seen as a new user and so won't be able to open those previous downloads. If you try to re-authorize without an Adobe ID - to go back to anonymous activation - you will be seen as a new anonymous user, and will still get an error.

If you try to re-download the same book from Ebook Central during the same download period, it will be seen as the same loan and will return this error when you attempt to open in ADE.

When your initial download period on Ebook Central has expired, you will then be able to re-download the book and open in ADE, because this will be seen as a fresh download.

For more information on library E-books see
E-Books at Penn State