Resetting your Mac System Management Controller (SMC) can be a solution. This is sometimes necessary to restore normal lower level system functionality to your Mac, particularly for power and hardware related troubles.
- Follower the SMC reset with an NVRAM or PRAM on your Mac ( see bottom of the page. )
How to reset the SMC on Mac notebooks
If you have a MacBook Pro (2018), skip ahead to the section that deals with your Mac.
To reset the SMC on a Mac notebook,
- Choose Apple menu > Shut Down.
- After your Mac shuts down, press Shift-Control-Option on the left side of the built-in keyboard, then press the power button at the same time. Hold these keys and the power button for 10 seconds. If you have a MacBook Pro with Touch ID, the Touch ID button is also the power button.
- Release all keys.
- Press the power button again to turn on your Mac.
Reset NVRAM or PRAM on your Mac
If your Mac has issues related to settings stored in NVRAM or PRAM, resetting it might help.
NVRAM (nonvolatile random-access memory) is a small amount of memory that your Mac uses to store certain settings and access them quickly. PRAM (Parameter RAM) stores similar information, and the steps for resetting NVRAM and PRAM are the same.
Settings that can be stored in NVRAM include sound volume, display resolution, startup-disk selection, time zone, and recent kernel panic information. The settings stored in NVRAM depend on your Mac and the devices that you're using with your Mac.
If you experience issues related to these settings or others, resetting NVRAM might help. For example, if your Mac starts up from a disk other than the one selected in Startup Disk preferences, or a question mark icon briefly appears before your Mac starts up, you might need to reset NVRAM.
How to reset NVRAM
Shut down your Mac, then turn it on and immediately press and hold these four keys together: Option, Command, P, and R. You can release the keys after about 20 seconds, during which your Mac might appear to restart.
- On Mac computers that play a startup sound, you can release the keys after the second startup sound.
- On Mac computers that have the Apple T2 Security Chip, you can release the keys after the Apple logo appears and disappears for the second time.