Safe mode (or safe boot) is a diagnostic mode of macOS. Starting your computer in safe mode is one of the most common troubleshooting and maintenance methods. This mode is designed to fix various macOS problems. Macreports has a lot of Mac troubleshooting articles. And most, if not all, suggest activating safe mode. It lets you troubleshoot what is preventing the operating system from functioning normally.
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Safe mode has many background maintenance features. In safe mode, your Mac:
- will disable all startup apps and items so that they will not load automatically
- will run a file repair
- will only allow essential kernel extensions
- will only load the built-in fonts, only fonts located in /System/Library/Fonts will be loaded.
- will disable all login items
- will delete some cache files: kernel cache, system cache and all font caches stored in /Library/Caches/com.apple.ATS/(uid)/ [uid: user ID]
How to turn on safe mode
Here is how you can boot into macOS safe mode:
- Turn off your Mac
- Turn on your Mac and immediately after hearing the startup tone, press and hold the Shift key.
- Keep holding the Shift key, wait for the login screen
- When you see the login screen, release the Shift key
- Your Mac is now in safe mode
- Log into your Mac
How to turn off safe mode
Here is how you can restore the system to its normal mode:
- Restart your Mac normally without pressing the Shift key. If you cannot exit safe mode, please see this article.
How to know if your Mac is in safe mode
When your computer is in safe mode, your computer will appear the same. So you may suspect that perhaps your Mac is not in safe mode. So how can you tell? There are two ways:
- Your lock / login screen will say “safe boot” in red in the menu bar:
- The other method is to use System Information. Here is how:
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