Disk Utility can find and repair errors related to the formatting and directory structure of a Mac disk. Errors can lead to unexpected behavior when using your Mac, and significant errors might even prevent your Mac from starting up completely.
All of a sudden my husband’s macbook could no longer open any OSX apps, including Safari, App Store, iMovie, Photos, etc. Once attempted to be opened, the app icons show a? Instead of the usual app icon. He would then get the following error: You can’t open the application because it may be damaged or incomplete. The App store maintains the list of apps users have purchased. In case if you need the app in future, then one can install it again without paying money again. To fix or repair the app in case if it’s broken is fairly simple. User just has to uninstall it and reinstall it again from the App Store.
Before proceeding, make sure that you have a current backup of your Mac, in case you need to recover damaged files or Disk Utility finds errors that it can't repair.
Open Disk Utility
Start up from macOS Recovery, then select Disk Utility from the Utilities window. Click Continue.
If you're not repairing the disk your Mac started up from, you don't need to start up from macOS Recovery: just open Disk Utility from the Utilities folder of your Applications folder.
Locate your disk in Disk Utility
Choose View > Show All Devices (if available) from the menu bar or toolbar in Disk Utility.
The sidebar in Disk Utility should now show each available disk or other storage device, beginning with your startup disk. And beneath each disk you should see any containers and volumes on that disk. Don't see your disk?
In this example, the startup disk (APPLE HDD) has one container and two volumes (Macintosh HD, Macintosh HD - Data). Your disk might not have a container, and it might have a different number of volumes.
Repair volumes, then containers, then disks
For each disk that you're repairing, start by selecting the last volume on that disk, then click the First Aid button or tab.
In this example, the last volume on the disk is Macintosh HD - Data.
Click Run to begin checking the selected volume for errors.
- If there is no Run button, click the Repair Disk button instead.
- If the button is dimmed and you can't click it, skip this step for the item you selected, and continue to the next item.
- If you're asked for a password to unlock the disk, enter your administrator password.
After Disk Utility is done checking the volume, select the next item above it in the sidebar, then run First Aid again. Keep moving up the list, running First Aid for each volume on the disk, then each container on the disk, then finally the disk itself.
In this example, the repair order is Macintosh HD - Data, then Macintosh HD, then Container disk2, then APPLE HDD.
If Disk Utility found errors that it can't repair
If Disk Utility found errors that it could not repair, use Disk Utility to erase (format) your disk.
If your disk doesn't appear in Disk Utility
If Disk Utility can't see your disk, it also can't see any containers or volumes on that disk. In that case, follow these steps:
- Shut down your Mac, then unplug all nonessential devices from your Mac.
- If you're repairing an external drive, make sure that it's connected directly to your Mac using a cable that you know is good. Then turn the drive off and back on.
- If your disk still doesn't appear in Disk Utility, your disk or Mac might need service. If you need help, please contact Apple Support.
Several users have reported that they receive the error message below when they attempt to upgrade to macOS Catalina.
Error Message: This copy of the Install macOS Catalina application is damaged, and can’t be used to install macOS.
Are you having this problem? This article explains how you can fix this macOS application damaged error.
Please try each step one at a time until you resolve your issue.
1. Please make sure that you are trying to update to macOS Catalina by going to Apple Menu > System Preferences > Software Update. Do not use any other non-Apple source, such as a third party web site.
2. Delete the damaged macOS version and retry to download again. The copy of the damaged file is located in /Applications folder. You can also use the Terminal to do this. Here is how:
- Open the Terminal app (Applications > Utilities) (you can use Spotlight)
- Copy and paste the following command
- Press enter, you may have to enter your admin password
This will delete the app, now you need to re-download and install Catalina. Simply click the Upgrade Now button.
How To Fix Damaged App Message On Macos Catalina
3. Try removing installinfo.plist. Here is how:
- Open Terminal and enter the followign command and press enter:
4. If still having this issue, this may be due to the invalid time on your Mac. You may have to correct this. Here is how:
- On your Mac, go to System Preferences > Date & Time. Is this showing the correct time and date? If not change it. And check the “set date and time automatically” box. Close this and retry again.
- If you are stuck before the OS installed (you are unable to access System Preferences), and then you may try the Terminal app to do this. Here is how:
- Click the Utilities menu (from the macOS Utilities menu) and select Terminal
- Enter the following command and hit enter
- date
- Is it the correct info? If not, change please by using the date {month}{day}{hour}{minute}{year} format. Brackets should be replaced with a two-digit number such as October 8, 2019 11:36 Am (today’s date and current time) would become date 1008113619
- Type this and press enter
- Now quit Terminal and try downloading Catalina again.
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See also: Apple ID Settings problem