This error is usually caused by one, or some combination, of the following three system settings:

• Incorrect clock time.
• Incorrect date.
• Incorrect time zone.

When you download a PDF or an EPUB, the Adobe activation records timestamp information from the Adobe activation server. This information is stored inside the book. When you attempt to open the book, this information is compared to your current system information. If your system has an incorrect time/date/time zone, then the activation server disallows the request and you cannot read the book.

Please carefully check the machine's system time, date, and time zone to be certain they match the time/date/zone when you purchased the PDF or EPUB. In most cases this will resolve the error.

Otherwise, the ACSM files can expire over time. So if you are still trying to access the same file downloaded a day or so ago this can also give the same error.

Please try logging in to your account on eBooks.com and downloading a new file, this should resolve the issue.

If you are still having difficulty authorising ADE please contact our support team. Please quote the error message when doing so.