Safe mode (sometimes called safe boot) is a way to start up your Mac so that it performs certain checks and prevents some software from automatically loading or opening. Starting your Mac in safe mode does the following:
Verifies your startup disk and attempts to repair directory issues, if needed
Loads only required kernel extensions
Prevents Startup Items and Login Items from opening automatically
Disables user-installed fonts
Deletes font caches, kernel cache, and other system cache files
If your Mac has an issue that goes away when you start up in safe mode, you can use this information to isolate the cause.
Start up in safe mode
To start up in safe mode:
Start or restart your Mac, then immediately press and hold the Shift key. The white Apple logo appears on your display. If you don’t see the Apple logo, learn what to do.
Release the shift key when you see the login window. If your startup disk is encrypted with FileVault, you might be asked to log in twice: once to unlock the startup disk, and again to log in to the Finder.
To leave safe mode, restart your Mac without pressing any keys during startup.
If your Mac doesn’t have a keyboard to start up in safe mode
If your Mac doesn’t have a keyboard available to start in safe mode, but you have remote access to your Mac, you can configure the Mac to startup in safe mode using the command line.
To start up in safe mode by opening Terminal.
Use the following Terminal command:
sudo nvram boot-args=”-x”
If you want to start in verbose mode as well, use this instead:
sudo nvram boot-args=”-x -v”
After using safe mode, use this Terminal command to return to a normal startup:
sudo nvram boot-args=””
Features aren’t available in safe mode
Some features of your Mac aren’t available when it’s started in safe mode:
You can’t play movies in DVD Player.
You can’t capture video in iMovie and some other video apps.
Some audio input or output devices might not work.
Some USB, FireWire, and Thunderbolt devices might not be available.
Wi-Fi networking might be limited or unavailable, depending on the Mac and macOS version you’re using.
Accessibility features like VoiceOver might not work as expected.
File sharing is disabled.