'Disk Utility can't repair this disk' Error

The Disk Utility that comes built-in with macOS is an incredibly handy and powerful tool that can be of great assistance when dealing with seemingly complex issues. Users can rely on it to perform a multitude of functions such as formatting disks, securely erasing data, and mounting a volume that is giving Finder troubles. The most important aspect of Disk Utility, however, is its ability to check for and then repair problems with the disk drives of the system. 

How to Repair a Disk with Disk Utility

Start by opening your Applications folder, then go to Utilities, navigate to Disk Utility, and launch it. Once inside, click view in the top left corner of the window. Select 'View all devices.' From the sidebar, choose the dirk or volume that you wish to repair.

Now, click on 'First Aid,' followed by 'Run' and then 'Continue.' There are a couple of different possibilities here:

• If you see a message stating that the disk is about to fail, go and create a backup of the data stored there as soon as possible.
• If you see a message stating that Disk Utility can't repair the disk, then start the process from scratch and try everything once more. 

NOTE: Keep in mind that if the disk you are trying to repair is the start-up disk of the system, you need to first boot the Mac into Recovery mode and then choose Disk Utility from the options there. To start your Mac in Recovery mode, restart the system and hold down Command+R on your system during boot. 

Make a Backup

If Disk Utility has failed to resolve the issue the second time as well, then the best option is to create a backup of the disk and then look for other solutions to the problem. There are numerous third-party apps that can help with the creation of the backup, but users can also take advantage of the Time Machine tool that comes with your macOS.  

To start the Time Machine, first, go to the Apple menu and then choose 'System Preferences.' Select Time Machine. Press the 'Select' button and choose the disk that you want to back up to. Tick the 'Show Time Machine in the menu bar' box. All that is left is to click on the Time Machine menu bar and then select 'Backup Now.'