MacBook Air turns off whenever lid is closed after High Sierra update Ever since I updated my MacBook Air to High Sierra, it turns off almost every time I close it. Sometimes when it is closed it'll actually restart - I can tell because it makes the Mac "ding" startup sound while the lid is still closed. Do you have any suggestions for how to fix this? 

Here are the full specs of the machine:

MacBook Air Mid 2012

4GB of Ram

13" Display

After more investigating, here are some further details:

When I press "Sleep" from the Apple menu and when I close the MacBook Air, either way the computer goes into a sleep state from which it cannot be woken. The only way to wake the computer when this happens is to do a long press on the power button (to turn off the computer) and then to do a short press on the power button (to turn it back on). When the computer comes back on it shows the "You shut down your computer because of a problem" error dialog. If I am using the computer and then I shut it and do not open it for awhile, I will sometimes hear the computer make the startup sound and the Apple logo on the back of the screen will light up while the laptop is closed.
The first thing I would try is resetting the System Management Controller.

Reset the SMC

On your particular Mac, the steps to follow are:


Shut down your MacBook Air
Unplug the power cable from your MacBook Air
For 10 seconds, press and hold at the same time the shiftcontroloption keys (on the left side of the built-in keyboard) and the power button
After 10 seconds let go of all keys and the power button 
Plug in the power cable
Turn your MacBook Air back on with the power button.


Once you've done this, test your MBA by using it as normal to see whether this was enough to rectify it.