I'm having the same issue! Please let me know if you figure it out!
Also having same problem. No help from the support department. I have tried the possible solution link provided by Chirag and it did not work.
My solution on a MacBook Pro with El Capitan
- 1. Opened my hidden Library folder
a. Opened Finder
b. Pushed & Held “Option” key and clicked “Go” in the title bar (“Library” appeared)
c. Clicked “Library” while Holding “Option” key
- 2. Went to /Application Support/Adobe/Digital Editions
- 3. Deleted the “activation.dat file”
- 4. Deleted Adobe Digital Editions (I did it with Clean My Mac 3 but you probably won’t need to use it for the deletion)
- 5. Emptied Trash
- 6. Reinstalled Adobe Digital Editions 4.5
- 7. Adobe Digital Editions opened authorization popup, which I filled out
- 7. My files now open perfectly