Restarting your Mac regularly is necessary to install important security and quality updates. Any Mac will be required to restart if it’s been running for more than 10 days.
You will be prompted to restart your Mac if it has been more than 10 days since your last restart. Don’t worry – you’ll have up to a day to defer the restart prior to it being mandatory.
And if you’re already restarting regularly, thanks! You won’t see any change if your Mac has been running for less than 10 days since the last restart.
If your computer has been running without a restart for more than 10 days, this window will appear with an option for you to defer for up to a day.
At the end of the deferral period, you’ll still have 15 minutes before a restart is forced.
Want to see how long a Mac has been running? Go to the lightning bolt menu in the upper right portion of the screen, and select Tools and information. The Uptime item in the submenu will show approximately how many days have passed since the last restart.