Mac OS 10.8 Mountain Lion

What you should know about Gatekeeper and installing new Apps

mountainlionMac OS 10.8 Mountain Lion only allows apps that are downloaded directly from the Apple app store to launch.  Apple calls this new security feature Gatekeeper.  In this article we'll provide an overview of Gatekeeper, including a walkthrough on how to bypass it to install software or drivers you've downloaded outside the Apple App Store.



When you attempt to open an app or installer from an unidentified developer, Gatekeeper will block the app from launching, and you'll be presented with the following warning:

gatekeeper error

Apple's Gatekeeper is designed "make it safer to download apps by protecting you from inadvertently installing malicious software on your Mac." With the advent of the new Apple App store, most Mac owners will be installing most or all of their software directly from this store.  However, there are situations in which you may want to install software or drivers which do downloaded from some other source.  For example:

  • Many software developers offer downloads on thier own web stores.  If you download software directly from the developer, not from the Apple App store, Mountian Lion's Gatekeeper will not allow it to launch.
  • If you use third party peripherals with your Mac, such as an Audio or Video Interface, you may need to install or update the devices drivers.  Mountain Lion's Gatekeeper may also prevent these installers from launching.

For more information about how Gatekeeper works, refer to the following article on Apple's site:


Overriding Gatekeeper for an individual app or installer

Gatekeeper is simple to override for an individual app. This is generally a safer and more secure option than overriding it for all apps.

  1. Right-click (or Ctrl+click) the app in the Finder and choose Open.
  2. A different different dialog box will appear that gives you the option to open the app. Choose Open.

    open warning
  3. The app will launch normally, and thatís it. It will be added to your computer's list of safe apps, and it will open without warnings in the future.  


Overriding Gatekeeper for an all apps on your computer

  1. In the upper-left corner of your screen, select the Apple menu and choose System Preferences.

    system preferences
  2. In the window that opens, select the Security & Privacy preferences pane.


  3. In the lower-left of the next screen, click the Lock icon to unlock this preferences pane for changes.  In the window that opens, enter your administrator password, and click Unlock.


    On the General tab select under the heading Allow applications downloaded from, the following three options are available:
    • Mac App Store - When this choice is selected, any apps not downloaded from the Mac App Store will be rejected when you try to launch them.
    • Mac App Store and identified developers - This is the new default setting in Mountain Lion. In addition to Mac App Store apps, it also allows any third-party apps that have been signed by an identified developer to run.
    • Anywhere - This choice uses the same set of rules as every previous version of Mac OS X. If an app isnít known malware and you approve it, it will open.
  4. If you want Mountain Lion to run every app regardless of where it was downloaded, select Anywhere.  

    three options

    This choice uses the same set of rules as every previous version of Mac OS X (10.7). If an app isnít known malware and you approve it, it opens., as seen in the picture below. Changing this setting requires that you enter an administratorís user name and password.
  5. An additional warning will appear (see below).  Choose Allow From Anywhere.

    second warning

    Now, all apps will open without warning, regardless of where they were downloaded.


Other Resources

Check out these other articles about Gatekeeper: