This error occurs when you try to open a DRM protected ebook in Apple's iBooks or Apple Books app.
Apple's ebook apps do not support Adobe DRM (the industry standard) so the ebook cannot be read in iBooks/Apple Books.
In order to read your ebook you need to download and install an app that is compatible with Adobe DRM.
If you are using a Mac please install Adobe Digital Editions. Please see our articles on
If you are using an iOS device please install our Ebook Reader app. Please see our articles on