If you’re experiencing issues with your Mac, then you can easily fix that by restarting it. I know it sounds odd, but it helps at times. However, if that doesn't fix the problem, then there are usual ways to go about solving the issue. One of the ways you can resolve them is by starting the mac in safe mode.
Not only does it help you test where the problem is, but it’s also one of the most common maintenance methods you can use with your computer.
We’re going to explain what Safe mode is, how you can boot your Mac in this state, and when you need to use it.
Activating safe mode allows you to troubleshoot any problem that prevents the operating system from functioning normally. It helps you figure out the problem based on how the computer reacts to the Safe Mode environment.
While in this mode, your Mac starts without loading the additional third-party programs. So you can test whether it’s the whole system or a particular program that’s causing issues.
That means only a minimal number of preferences, system extensions, and fonts that need to run will start up with your computer so that you can isolate the issues and troubleshoot accordingly.
Safe Mode can get your computer up and running all over again whenever issues brought about by corrupt data or apps, damaged fonts, and preference files, or software installation issues arise.
You can use it to resolve any problems that keep your Mac from starting up or startup disk related issues, including apps not launching or those causing your computer to crash, freeze, or shutdown.
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What Happens When Your Mac Is in Safe Mode
Several things happen when you start your Mac in Safe Mode. Specifically, it does the following:
You Mac loads required kernel extensions needed to run macOS.
It verifies your startup drive by performing a directory check and attempts repairs for any issues.
It prevents startup and login items from automatically opening at startup.
It disables user-installed (third-party) fonts besides those found in System/Library/Fonts supplied by Apple.
It deletes all font caches and moves them to the trash, including kernel cache and other system cache files.
It also deletes the dynamic loader cache known for causing the blue screen freeze during startup.
It disables or limits features such as the DVD Player, iMovie (won’t capture video), internal and/or external modems, AirPort cards (depending on the version and macOS version in use), Quartz Extreme, and Network file sharing.
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How to Start up Your Mac in Safe Mode
To start up in Safe Mode, take the steps below:
Step 1: Start or restart your Mac.
Step 2: Press and hold down the Shift key immediately when you hear the chime. You’ll see the Apple logo appear on your screen.
Step 3:Release the Shift key once the login window comes up. If your Mac’s startup disk is encrypted with FileVault, you’ll log in twice – the first login unlocks the startup disk, while the second logs you in the Finder.
Note: Once you establish the problem, you can leave Safe Mode by restarting your Mac without pressing any keys at startup.
How to Tell Whether Your Mac Is in Safe Mode
You can tell whether your Mac is in Safe Mode by using the System Information app. The System Information app (also known as System Profiler in some versions of OS X) shows a summary of information about your Mac’s software, hardware, network and other information.
To go to the System Information app, click Apple menu> About This Mac to open an overview of your Mac computer, including its model, memory, processor, serial number, and macOS version.
You can see more information by clicking the System Report button.
Under the Software section in System Information, you’ll see the text “Safe” instead of “Normal” next to the Boot Mode.
The login window will also show the Safe Boot label on the top right side of the screen when in Safe Mode.
What to Do When Your Mac Won’t Turn on or Start up in Safe Mode
Here are some things to check for when your Mac won’t turn on, or it powers on but doesn’t complete the startup process:
Check for power-related issues such as sounds from the fan or hard disk among other startup sounds. Check also for lights like the sleep indicator light, Caps Lock key, or backlit keyboard, if you have one.
You can also check that it’s receiving power by ensuring the power cable is undamaged and plugged in securely into a working power outlet.
Check that you’re using the right power cable and adapter, and if you’re using an external display, power it on and ensure it doesn’t have other display problems. Turn up your display’s brightness from the built-in keyboard.
Check other startup issues if it doesn’t finish starting up such as a recently installed hard disk/SSD or memory, and ensure that it’s compatible and correctly installed. You can also remove and test with the original disk or memory.