The "macOS could not be installed on your computer" error is one of the last ones you want to see. It pops up when you're updating your Mac's operating system but can't complete the operation. Despite the wording, it doesn't mean your installation will never work. It just means it failed that one time.

The bad news is this error could be occurring due to a number of reasons. The good news is you can get your Mac back up and functional with a little work.

How to Fix the 'macOS Could Not Be Installed' Error

Fixing the "macOS Could Not Be Installed" error may require some patience. It's best to start with the simple fixes, which often solve the problem, but if they don't, you have other options. Here are the approaches to try.

1. Restart and try the installation again. This may seem counterintuitive to redo the thing that didn't work, but sometimes a restart is all your Mac needs to sort itself out.

2. Check the Date & Time setting. If the displayed date and time don't match reality, this could be the problem. Restart your Mac again if necessary, and then go toSystem Preferences>General>Date & Time. Click thelockicon and enter your password (if necessary) to enable changes. Then clickSet date and time automatically. After this, try the installation again to see if it works.

   

3. Free up space. In some cases, macOS fails to install because there isn't enough room on the hard drive. To see how much is available, click theApple logoand selectAbout This Mac>More Info>Storage Settings. You'll see a breakdown of what's living on your computer.

   Hover your mouse over the white space to the right of this bar to learn how much space is free. If it seems low, move some nonessential files off temporarily to see if that lets the installation proceed.

   

   Later versions of macOS also include a Manage option that offers suggestions and guidance to help you find things to remove.

4. Delete the installer. Find the macOS Installer in your Finder'sDownloadsfolder and drag it to the Trash. Then, download it again and retry.

   You may need to force restart your Mac by holding down thePowerbutton until it shuts down. Afterward, turn the Mac back on. You may also want to hold downShiftduring the restart to boot up in Safe Mode so the installer doesn't try to run again.

5. Reset the NVRAM. This tiny chunk of memory stores basic information such as the time, monitor resolution, and which disk to start up from. You may need to go back into System Preferences to switch any settings this changed, but you can try the installation again before that to make sure the problem is resolved.

6. Restore from a backup. If you use Time Machine to regularly back up your Mac, you can go back to an earlier state using Recovery Mode to see if it's more compatible with the installer.

   1. Make sure your backup drive is attached. Then, restart your computer and holdCommand+Runtil the Apple logo appears. Instead of going to the Desktop, your computer prompts you to choose the main language and then opens a window called macOS Utilities.
   2. In macOS Utilities, clickRestore From Time Machine Backup. Then, clickContinue.
   3. You'll come to an intermediate screen with some information about what you're about to do. ClickContinueto move ahead.
   4. Choose the drive where you store your backups and clickContinueagain, which takes you to a screen where you can choose your most recent backup. Afterward, clickContinueagain.
   5. Your computer restores the earlier backup, and you can see if the installation works.

7. Run Disk First Aid. This may help if you're getting the "Unable to mount volume" error. First Aid checks the internal hard drive and makes any fixes it can. It may even be able to mount the volume after it's done. Then you can retry the installation.

Still Need Help?

If none of the above worked, it may be time to turn your computer over to the professionals. Check out our guide on how to get your computer fixed for instructions on finding someone to solve the problem and what you need to do to prep your Mac for service.

Causes of the 'macOS Could Not Be Installed' Error

Several issues could cause the problem. However, the error screen should give you some idea of what's gone amiss.

Here are some messages you might see underneath the warning:

• The pat /System/Installation/Packages/OSInstall.mpkg appears to be missing or damaged.
• An error occurred installing macOS.
• Unable to unmount volume for repair.
• Storage system verify or repair failed.
• An error occurred while verifying firmware.

Some of these offer more information than others, but they point to different stages of the installation that failed. The following steps and fixes should sort out any of the problems mentioned above.

• Can I install macOS on my Windows PC?

  Yes. To install macOS on Windows, you need a fresh copy of macOS, a USB drive, free tools called UniBeast and MultiBeast, and compatible PC hardware.

• Can I install macOS for free?

  Yes. As long as you have a Mac computer, you can install any compatible version of macOS for free.
  

• How do I clean install macOS?

  Use Recovery Mode to reinstall macOS without erasing your boot drive. If this doesn't fix your problem, you can erase the boot drive and perform a fresh reinstall. Only use a bootable USB installer to reinstall macOS if you can't boot into Recovery Mode at all.