How to fix 'macOS Could Not Be Installed on Your Computer' Error

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 that 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.

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.

How to fix ‘macOS Could Not Be Installed’ Error

Fixing the “macOS Could Not Be Installed” error may require some patience. It’s best to start with simple fixes, which often solve the problem, but if they don’t, you have other options.

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.
Check the Date & Time setting. If the displayed date and time don’t match reality, this could be the problem.
Free up space. In some cases, macOS fails to install because there isn’t enough room on the hard drive.
Delete the installer. Find the macOS Installer in your Finder’s Downloads folder and drag it to the Trash. Then, download it again and retry.
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.
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.
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.