The macOS Sierra 10.12.3 update improves the stability, compatibility, and security of your Mac.
You can install this update using the MacOS Sierra Developer Beta Access Utility:
• If you have already installed the new "MacOS Sierra Developer Beta Access Utility”, choose "Software Update" from the Apple menu. Otherwise, proceed with the following steps.
• Log into your Apple Developer account and download the "MacOS Sierra Developer Beta Access Utility".
• After running the installer, the Mac App Store will open automatically. Click the Updates panel and the latest version of macOS developer beta will be available for download.
• When a newer seed build is available, you will receive a notification to update from the Mac App Store. Click the notification to begin the installation. New release notes will be posted in Downloads on the Apple Developer Program website.
• To stop receiving new developer beta builds, go to the App Store in System Preferences and where it says "Your computer is set to receive beta software updates", click the "Change..." button. Then click the Do Not Show Beta Software Updates button in the dialog box.
Download the MacOS Sierra Developer Beta Access Utility from the link below.