Since OS X 10.2 Jaguar, Apple has been offering Safe Mode (also known as Safe Boot) as a way of troubleshooting problems on your Mac. These problems can be anything from apps not starting, crashing, shutting down to causing your Mac to freeze, stutter or have problems booting up correctly.
What Is OS X Safe Mode?
Similar to safe mode on Windows OS, macOS Safe Boot mode was designed for troubleshooting purposes. When booting in safe mode, you allow your Mac to start with a minimal number of extensions, fonts, and preferences. In other words, safe mode is a dressed down version of the operating system, which, in many cases, can become a key troubleshooting step when trying to deal with problems on your Mac. It is also the recommended way of diagnosing problems, which you may encounter on your Mac as you use it. Sometimes you will find that the issue cannot be dealt with otherwise; in other cases, safe booting will allow distinguishing between software- and hardware-based problems.
Why Use Apple Safe Mode?
As already mentioned, some of Mac’s problems can be resolved by booting up in safe mode. In some cases, safe boot can even help deal with issues that prevent your Mac from starting up.
Upon searching through Apple discussions or power user forums, you will often find safe boot being recommended as the first step to resolving absolutely any kind of Mac problem you encounter. In the majority of cases, this can be true because safe mode clears out the caches, which typically cause issues when they get corrupted.
In fact, here is a quick list of cases when you may want to use safe mode:
- When you suspect an app is causing problems.
- When your Mac is running overall slow.
- When Mac is sluggish at startup.
Keep in mind, using safe mode will clear cache unconditionally, which may lead to slower reboots in the beginning until the relevant cache is rebuilt.
You will also find other reasons users choose to boot into safe mode such as to remove an app that won’t uninstall seamlessly. Some particularly ‘sticky’ apps may attach to system processes, thereby making it difficult to terminate them under a normal mode. It is a totally different setting when no processes of secondary value are loaded up.
Booting Mac in Safe Mode: What it Does/Doesn’t Do
Although certain cure-it-all mythology is attached to macOS safe mode, it, unfortunately, is not a universal fix to all of Mac’s problems. To better understand which of the issues can be resolved by safe booting, you will need to know which processes are taking place. Here is what safe boot will do during a startup process:
- Run a startup drive directory check.
- Load bare minimum kernel extensions essential to running macOS.
- Disable user-installed third-party fonts except the ones located in /System/Library/Fonts.
- Clear all cache.
- Disable all login items set to run at startup.
- Remove dynamic loader cache to fix blue screen problems on OS X 10.5.6 and above.
Aside from repairs listed above, there is not much you can do in safe mode. Safe mode’s main purpose is to help diagnose problems and test your Mac. For instance, if the issue does not occur in safe mode, then it is a software-based trouble likely to be caused by a third-party app, service, faulty kernel extension or even corrupted cache.
How to Boot into MacBook Pro Safe Mode (and Other Macs As Well)
Whenever you need to boot into safe mode on your MacBook Pro (or any Mac using the wired keyboard), follow these steps:
- Shut Down your MacBook.
- Hold down the Shift key.
- Start your MacBook back up.
- Release Shift key at login window or desktop.
If you are using a Mac computer with Bluetooth keyboard, then do the following:
- Shut Down your Mac.
- Start your Mac back up.
- Hold down the Shift key when you hear Mac startup sound.
- Release Shift key at login window or desktop.
After logging in, you will quickly notice that, unlike Windows, macOS safe mode does not differ visually and it may not be evident whether you’ve managed to boot to safe mode. The first indication should be at the login screen menu bar where you will find ‘Safe Boot’ written next to the clock.
If you have already passed the login screen, you can check which mode you’ve booted by opening Apple Menu > About This Mac > System Report > Software and you will find the indication under Boot Mode.
Another sure way of telling you’re in safe mode is when your Mac works noticeably slower. This is due to loading bare minimum software needed for OS to function. It means that even your graphics will be accelerated only by default drivers.
To conclude, Safe Mode is a reliable and safe way of troubleshooting a problematic Mac. Using safe boot, you can isolate the issue, delete rooted apps, clear caches and fix unpleasant bugs. Yet, even when your Mac feels well, occasionally booting into safe mode can serve as a basic maintenance procedure.