When you activate Adobe Digital Editions, do you receive an error? If so, try the solutions on this page to resolve the issue.



This error occurs when the authorization information is damaged. Follow the steps below to rebuild the activation file.

Mac OS

  1. Open Adobe Digital Editions.
  2. Press Command+Shift+D to deauthorize Adobe Digital Editions.
  3. Select Erase Authorization.
  4. Click OK and quit Adobe Digital Editions.
  5. Navigate to /Users//Library/Application Support/Adobe/Digital Editions and drag the activation.dat file to the trash.
    If you are using 10.7, see Access hidden library files | Mac OS 10.7 and later.
  6. Open Adobe Digital Editions and reauthorize.

Windows XP/Vista/7

  1. Open Adobe Digital Editions.
  2. Press Control+Shift+D to deauthorize Adobe Digital Editions.
  3. Select Erase Authorization.
  4. Click OK and quit Adobe Digital Editions.

Disclaimer: The following task requires you to modify the Windows registry. The registry contains system-related information that is critical to your computer and applications. Before you modify the registry, make a backup copy of it. Adobe doesn't provide support for problems that arise from improperly modifying the registry.

For more information about the Windows registry or the Registry Editor, see the Microsoft Support site

If the deauthorizing process is unsuccessful on Windows, it is possible to modify the registry to remove the activation information.

  1. Close all applications.
  2. Choose Start > Run.
  3. In the Open text box, type regedit and then press Enter. The Registry Editor opens.
  4. In the left pane of the Registry Editor, locate the following registry key: HKEY_CURRENT_USER\Software\Adobe\Adept
  5. Select the Adept key.
  6. Choose File > Export.
  7. In the Export Registry File dialog box, select Selected Branch under Export Range. Enter a name and location for the backup registry key, and then click Save.
  8. Right-click the Adept key and choose Delete.
  9. In the Confirm Key Delete dialog, click OK.
  10. Close the Registry Editor.
  11. Open Adobe Digital Editions and reauthorize.



This error may occur when you activate Adobe Digital Editions or read epubs. To resolve this issue, make sure that the machine’s system time, date, and time zone match the time/date/zone when you purchased the PDF or epub.

Additional information

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

One of the following system settings (or a combination of them) causes this error:

  • Incorrect clock time
  • Incorrect date
  • Incorrect time zone

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