The Mac OS X (macOS) “won’t shutdown” (slow shutdown) problem

Since upgrading to Mac OS X 10.9 I’ve experienced the problem other people have reported, where their Mac won’t shutdown, or shuts down very slowly. We had a huge lightning storm roll in a few days ago, and when my 2008 iMac didn’t shut down after three minutes of waiting, I finally had to press and hold the button on the back to force it to shut down.

Since then I’m glad to say that the following series of defaults write commands has helped my iMac to shut down much more quickly:

sudo defaults write /System/Library/LaunchDaemons/com.apple.securityd ExitTimeOut -int 5
sudo defaults write /System/Library/LaunchDaemons/com.apple.mDNSResponder ExitTimeOut -int 5
sudo defaults write /System/Library/LaunchDaemons/com.apple.diskarbitrationd ExitTimeOut -int 5
sudo defaults write /System/Library/LaunchDaemons/com.apple.coreservices.appleevents ExitTimeOut -int 5
sudo defaults write /System/Library/LaunchAgents/com.apple.coreservices.appleid.authentication ExitTimeOut -int 5

How to apply the fix

As a word of caution, if you’re not comfortable with what’s going on here, don’t enter these commands yourself. Contact your local geek and ask them to do it, or at least ask them to review what I’ve written here and see if they can help walk you through the process. (I’m not responsible for you entering commands and messing up your Mac; you’ve been warned.)

The way this works is that you have to enter these commands in a Mac Terminal. If you haven’t used it before, you open the Terminal application by clicking Applications; then scroll down if necessary to click Utilities; then click Terminal at the bottom of that list of applications.

When the Terminal application opens, enter the first command at the command line:

sudo defaults write /System/Library/LaunchDaemons/com.apple.securityd ExitTimeOut -int 5

The reason you only enter one command is because your Mac will prompt you for your administrator password. This is legit; you’re modifying properties that affect the entire system, not just your account.

Once you’ve entered the admin password once, you don’t need to use it again for approximately five minutes, so now you can just copy and paste the last four commands all at once:

sudo defaults write /System/Library/LaunchDaemons/com.apple.mDNSResponder ExitTimeOut -int 5
sudo defaults write /System/Library/LaunchDaemons/com.apple.diskarbitrationd ExitTimeOut -int 5
sudo defaults write /System/Library/LaunchDaemons/com.apple.coreservices.appleevents ExitTimeOut -int 5
sudo defaults write /System/Library/LaunchAgents/com.apple.coreservices.appleid.authentication ExitTimeOut -int 5

If you now reboot your Mac, you should see it reboot much faster. As mentioned at the beginning, I had to wait over three minutes for a recent shutdown, but after issuing these commands the reboot happened much faster, in less than fifteen seconds.

More information on the Mac shutdown problem

For more information on this Mac OS X 10.9 shutdown problem, search Google for those search terms. FWIW, I found these instructions on many websites, including this CNet article.