How to start a Mac in Safe Mode

Here's how to start a Mac in Safe Mode so you can troubleshoot and fix issues

Safe Mode is a stripped down version of the Mac operating system that can be useful if you are trying to troubleshoot issues with your Mac: perhaps it is running slowly, maybe an app is causing problems, you might be having problems with crashes or application freezes, or, worse, your Mac might not be booting up at all.

In this tutorial we will explain how to start up in Safe Mode, why you would want to use Safe Mode, including what it does, and doesn't do, how you know you are in Safe Mode, and what to do if your Mac automaticaly starts up in Safe Mode.

Why use Safe Mode

Using Safe Mode can help you resolve issues that are stopping your Mac from starting up, or any issues related to your startup disk.

Within the power user community there’s a certain mythology attached to booting into safe mode on the Mac. Some people recommend it as a first step should your Mac encounter absolutely any kind of problem. This is probably effective because the caches are cleared by safe mode, and these can become corrupted.

Here are some of the reasons why you might want to use Safe Mode:

• If your Mac stalled during start up
• If you think an app is causing problems
• If your Mac is running very slowly (starting in Safe Mode will clear the cache and could speed things up)

Do bear in mind that cleaning the caches using either method may make for a slower Mac in the first few reboots after it’s undertaken - after all, the whole purpose of caches is to make your Mac faster.

Some people use safe mode to uninstall apps that otherwise prove "sticky" - that is to say, they’re impossible to get rid of in normal operating mode because they’re tied to a system service that won’t terminate. In safe mode all non-essential services aren't loaded, overcoming this hurdle.

If the issue doesn’t happen when you start in Safe Mode it may indicate one of the following:

• You may have incompatible login items.
• If after using Safe Mode you reboot and the issue doesn’t repeat it is likely that the problem was related to a cache or directory issue that has been fixed when you ran Safe Mode.

How do I start a Mac in Safe Mode

Follow these steps to Safe Boot your Mac:

1. Start your Mac
2. Press and hold the Shift key
3. The Apple logo should appear
4. When the login window appears release the shift key and log in
5. You may be required to log in twice if you have FileVault turned on

What Safe Mode does/doesn’t do

Safe Mode performs certain checks and prevents some software from automatically loading or opening when you start up your Mac. When you boot in Safe Mode...

• Only essential kernel extensions are loaded (a.k.a. ketxs, or hardware and software drivers)
• Startup apps and login apps/services are not loaded
• Fonts you’ve manually installed are not loaded

Additionally, system and font caches are automatically cleaned, and as part of the boot procedure the hard disk is verified and attempts made to repair issues with directories - a little like Windows’ FDISK command-line app, although what happens is identical to what would happen if you click the Repair Disk button found in of macOS’s Disk Utility.

So, what can you do in safe mode? Not much! Aside from the repairs mentioned above, safe mode is designed to let you test your Mac. If a problem you’ve been having doesn’t occur when you boot to safe mode then it’s a safe bet it’s related to a problematic kernel extension (perhaps faulty hardware that kernel extension accesses), or – and this is more likely – it’s related to a third-party app or service configured to start with macOS.

How to prune your startup app list

1. Open System Preferences and click the Users & Groups icon.
2. Select your username at the left.
3. Click the Login Items tab.
4. Select an item then click the minus button beneath to remove it.

Some apps and services hide away in system folders, however, and pruning them is only for advanced users. Removing kernel modules is again only for experts, although on modern releases of macOS it’s pretty hard for developers and hardware vendors to install third-party modules thanks to the requirement for them to be digitally signed, so this is much less likely to be the cause of any issues.

Note: Don’t try and do actual work in safe mode. Some apps simply won’t work and the whole system will be slow and unresponsive. However, for problem solving there’s little doubt that safe mode has its uses.

How do you know you are in Safe Mode

Unlike with Windows there’s no text on the desktop once Safe Mode starts to show you’re booted into it, and you won’t be limited to a tell-tale low screen resolution either. However, clues will be present in the fact the system might seem slow to respond, and animations might appear jerky.

To check if you are in Safe Mode follow these steps:

1. Click on the Apple logo in the menu (top left).
2. Click in About This Mac.
3. Click on System Report.
4. Click on Software and check what the Boot Mode is listed as - it will say Safe if you are in Safe Mode, otherwise it will say Normal.

Other ways you can tell you are in Safe Mode:

• You might see your screen blink when the login screen appears during startup.
• Depending on the version of the Mac operating system you are using the screen may be grey and a progress bar may appear under the Apple logo during start up. In newer versions of macOS the start up will appear as normal other than potentially having to log in twice.
• Your Mac will be slow.

When you are in Safe Mode you won’t be able to: 

• Capture video in some video apps.
• Audio devices might not work.
• Some USB or Thunderbolt devices might not be available.
• WiFi networking may not be available.
• File sharing will be disabled.
• Some graphical elements will not appear, for example the dock (shown below) may look grey rather than transparent.

If the keyboard is not connected to the Mac computer, and therefore it is impossible to press the key to start the computer in safe mode, but there is remote access to the computer, you can start it in safe mode using the command line.

1. Go to the command line by opening the Terminal program window remotely or by logging in using SSH.
2. In the "Terminal" program window, enter the following command:

sudo nvram boot-args="-x"

If you need to run in detailed logging mode, use the command:

sudo nvram boot-args="-x -v"

3. To disable startup in safe mode and restore normal startup mode, enter this command in the "Terminal" program window:

sudo nvram boot-args=""

What to do if your Mac automatically starts in Safe Mode

If it detects an issue which could be fixed by Safe Mode your Mac might automatically boot in Safe Mode and attempt to repair it. Hopefully this will fix the issue, but if it doesn’t and your Mac keeps restarting in Safe Mode then you should contact Apple Support, an Apple Authorised Service Provider or visit an Apple Store for help.

Another possibility is that the Shift key is stuck and that is causing Safe Mode to be implemented when you start up the Mac.

How to I turn off safe boot on Mac? How do I get out of safe boot on my Mac?

To exit Safe Mode just shut down your Mac and restart it (this time without pressing Shift).

Shutting down in Safe Mode may take a little longer than it would normally take to shut down. Be patient and don’t interrupt the process or use the Power button to switch off your Mac.

Problems with Mac Safe Mode, Safe Mode not working

You may be concerned if your Mac may take longer to boot up in Safe Mode. There is probably no cause for concern. It will take longer as the Mac will be performing a directory check of your startup disk.

If your Mac restarts or shuts down when you use Safe Mode this may be because your Mac has already repaired an issue with the startup disk, in which case your Mac has automatically restarted.

However, if your Mac repeatedly restarts or shuts down while in safe mode, Apple advises that you contact Apple Support or consult with an Apple Authorised Service Provider or visit an Apple Store for help.