With each release, Apple beefs up the security of its operating system — which is a good thing, but not appreciated by power-users, or even semi-power-users.
With macOS Sierra, a major security-related change is how Gatekeeper functions.
First, what is Gatekeeper? From Apple support:
Gatekeeper is a new feature in Mountain Lion and OS X Lion v10.7.5 that builds on OS X’s existing malware checks to help protect your Mac from malware and misbehaving apps downloaded from the Internet.
Essentially, Gatekeeper ensures that the apps you install are safe. It does so by allowing only apps that are downloaded from the App Store or from “Identified Developers.” This is the default behavior of Gatekeeper.
You can view Gatekeeper options by going to System Preferences > Security & Privacy > General tab.
If you want to run apps created by unidentified developers, you have two options:
Option 1: Instead of double-clicking on an app, right-click on the app and select “Open.” But you will have to do this each time you want to launch those apps.
Option 2: The second, a more permanent option is to change the default behavior of Gatekeeper. Simply enable “Anywhere” option in Gatekeeper. This will allow you to run apps downloaded from anywhere in a standard manner, i.e. by double-clicking on it.
With macOS Sierra, Apple has changed the default Gatekeeper behavior. The “Anywhere” option is no longer available in Gatekeeper, which means, Option 2 discussed above is not available in Sierra. However, Option 1 is still available — you can still open apps from unidentified developers by right-clicking on it and selecting open.
However, if you are a true warrior and would like to change the default Gatekeeper behavior in Sierra, there is a quick fix for that.
Simple run this command on terminal:
Before you run this command, understand what it is. spctl is a command line tool to manage signing for Gatekeeper. This file modifies the information stored in /var/db/SystemPolicy. More information on spctl is available on Apple developer site.
After you run the command, you will see “Anywhere” option in Gatekeeper.