For this problem, you need to deauthorize and authorize ADE again.
Help -> Erase authorization.
ADE will be deauhorized.
Now again AUTHORIZE ADE
Help-> authorize computer.
Error will be fixed !!
When i try and erase authorisation, it comes up with the message: "Unable to erase authorisation. Please try after some time"
I had actually tried this earlier today as well after reading in another thread, and the message was the same. Any further suggestions?
If due to some reason, you are unable to deauthorize ADE, follow the below steps:
Ok, try the following way to access activation.dat:
1. Go-> Go to folder.
Go to folder dialog will appear.
2. Type ~/Library/Application Support/Adobe/Digital Editions
drag the activation.dat file to the trash.
ADE will be deauthorized now.
Now Authorize ADE again.