One change that has found its way into MacOS Sierra that has been impacting a number of people is the removal of the user’s ability to easy exempt applications from Gatekeeper’s scrutiny. This is an issue when a user tries to open application is not signed by an “approved” developer. They will be prompted with a warning similar to this one:
It is also possible the warning will say that the application is damaged and should be moved to the Trash. In either case, the problem is MacOS’s built in security feature called Gatekeeper. In previous version of the OS, the user could easily open Security Preferences and tell the system to open the application anyway. For some reason, Apple decided to remove the ability to easily do this via the GUI. However, it is still possible to perform this function via the CLI (Terminal).
There are two ways to accomplish this. The first way is to temporarily disable Gatekeeper, open the application, then re-enable Gatekeeper. Once the application has been opened once, Gatekeeper will stop bothering you about it on subsequent launches. In order to disable Gatekeeper you need to run the following command in Terminal (then enter your admin password):
sudo spctl --master-disable
Once you’ve done this, open the application and run the command:
sudo spctl --master-enable
The other way to accomplish this is to manually add an application to the Gatekeeper whitelist. In order to do this you will need to run the command:
sudo spctl --add /Path/To/Application.app
If you ever wish to remove the application from the whitelist, it is as easy as changing –add to –remove:
sudo spctl --remove /Path/To/Application.app
Either of these methods should allow you to open any application you please on MacOS Sierra.
Note: For security reason you should not leave Gatekeeper disabled indefinitely. If you are using the disable method, you should be sure to reenable it immediately after opening the “unidentified” or “damaged” application.