I’m often asked how to speed up a Mac that seems to have slowed, or how to fix a regularly crashing app. For these and many other performance issues, the first thing I generally do is try repairing the Mac’s disk permissions.
Every file on your computer has specific permissions associated with it. These permissions can become skewed over time, which can cause all sorts of seemingly inexplicable behaviors from your Mac. The good news is that fixing these permissions is both quick and easy.
First, make sure that Finder is active. You can do this by clicking your desktop. You’ll know that you’re in Finder when it says FINDER near the left side of the menu bar at the top of your screen.
Once in Finder, choose GO, UTILITIES from the menu bar. In the Utilities folder double-click Disk Utility to open it.
The field on the left of the Disk Utility lists every disk that your Mac can see, including its internal hard drive. This is usually called Macintosh HD and is near the top of the list.
Click your internal hard drive in the list, then click REPAIR DISK PERMISSIONS.
This starts the permission repair. The field in the middle of Disk Utility will show the status as it repairs. It will list any errors it finds, and how it dealt with them. When it’s finished, it will say, “Permissions repair complete,” at the bottom of the list.
When the permission repair is finished, it’s a good idea to reboot your Mac. Hopefully the issues that prompted the repair will now be gone. If not, then you’ve eliminated one of the most common culprits and can move on to the next troubleshooting step.
Jason Merrill, Mac & iOS Consultant