ADE Installer can't be opened because it is from an unidentified developer

"Digital Editions 4.5 Installer.pkg can't be opened because it is from an unidentified developer."

This error occurs because your computer is set up such that it will only let programs install that have been vetted by Apple. This is general this is a good security measure, but it can sometimes cause issues like this.

There are several ways to fix this. Solution 1 works in most cases. If necessary, try them in the following order:


  • Right-click (or control-click) the application in question and choose “Open”
  • Click the “Open” button at the next dialog warning to launch the app anyway


  • Hold down the control button and then click the "DMG" (software installer file), and select open.
  • The installer window will popup.
  • Do the same thing to the installation package; hold down the control button, click it and select open.


To override your security settings and open the app:

  • In the Finder, locate the app you want to open. (Don’t use Launchpad to do this. Launchpad doesn’t allow you to access the shortcut menu.)
  • Control-click the app icon, then choose Open from the shortcut menu.
  • Click Open.

The app is now saved as an exception to your security settings, and you can open it in the future by double-clicking it just as you can any registered app.


  • Choose Apple menu > System Preferences, click Security & Privacy, then click General.
  • You can grant an exception for a blocked app by clicking the “Open Anyway” button in the General pane. This button is available for about an hour after you try to open the app.

If you are still receiving the error please contact our support team. Please quote the error message when doing so.

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