What to do if macOS installation couldn t be completed?

Installing a new version of macOS on your Mac should be a straightforward process, but sometimes an error can occur that prevents the installation from completing successfully. The message “macOS could not be installed on your computer” or “The macOS installation couldn’t be completed” indicates there was an issue during the installation process.

There are several potential causes for the macOS installation not completing properly. The good news is there are steps you can take to troubleshoot and resolve the issue to get macOS installed on your Mac.

What Causes macOS Installation To Fail?

Here are some of the common reasons why a macOS installation may not complete successfully:

  • Not enough disk space – The macOS installer requires a minimum amount of available storage space on the startup disk to complete. If your disk is low on space, it can prevent installation.
  • Incompatible hardware – Some older Macs have hardware that is not supported by the latest macOS versions. This could block installation.
  • Corrupted installer files – If the macOS installer application or the installation payload is corrupted, it could result in errors during the process.
  • Problems with the startup disk – Issues like corruption, errors, or an unsupported format on the Mac’s boot drive can interfere with installation.
  • Third-party kernel extensions – Certain kernel extensions installed on your system could cause a conflict and installation failure.
  • Temporary glitch – Sometimes a temporary software glitch or unexpected restart can interrupt the installation.

Finding out the specific reason your macOS installation was unsuccessful is key to resolving the problem. Next, we’ll go over some steps to troubleshoot and fix it.

1. Check Your macOS Version Compatibility

The first thing to check is whether your Mac model and hardware configuration supports the version of macOS you are trying to install. Apple lists the system requirements and compatible Mac models on their website:

  • macOS Ventura – compatible on Macs from 2017 and later
  • macOS Monterey – compatible on Macs from 2015 and later
  • macOS Big Sur – compatible on Macs from 2013 and later

If you are trying to install a version of macOS your Mac or hardware does not support, the installation will fail. Make sure to upgrade to a compatible macOS version.

Use System Information to Check Hardware Compatibility

You can further verify your hardware is compatible by checking the System Information app on your Mac:

  1. Go to Apple menu > About This Mac
  2. Click System Report
  3. Go to Hardware and review components like Processor, Memory, Graphics, and Disk Drives
  4. Compare specifications to macOS minimum requirements

This will confirm all your hardware meets the minimum criteria for installing and running the macOS version you want. If certain components are too outdated, a hardware upgrade may be necessary.

2. Verify Your Startup Disk Has Sufficient Space

Another common culprit for a failed macOS install is not having enough free disk space available. Here’s how to check:

  1. Go to Apple menu > About This Mac
  2. Look at the Storage section
  3. Check that Available space meets minimum disk space requirements
    • macOS Ventura: 35-40 GB free space
    • macOS Monterey: 35-40 GB free space
    • macOS Big Sur: 35-40 GB free space

If your available disk space is lower than the requirement, you need to free up room before attempting the installation again. Here are some tips:

  • Empty Trash to delete unnecessary files
  • Use the Storage Management tool to remove old, large files
  • Delete unused apps and games
  • Store files like photos and movies on an external hard drive
  • Upgrade to a larger internal hard drive if necessary

Clearing sufficient storage through these steps will open up the space the macOS installer needs.

3. Disconnect External Drives and Peripherals

Another simple step is to disconnect any external devices connected to your Mac before installation:

  • External USB hard drives and SSDs
  • SD memory cards and other media
  • Printers, scanners, and other peripherals
  • Thunderbolt and DisplayPort devices

Having these extra devices hooked up during installation can sometimes interfere with the process. Safely eject and disconnect them prior to installation.

Additionally, make sure your Mac is connected to power and has a stable internet connection during installation. This prevents any power or connectivity disruptions during the process.

4. Run First Aid to Check Startup Disk Errors

Disk errors on your Mac’s startup drive can also lead to issues with macOS installation. To check for errors:

  1. Restart your Mac and hold down Command + R to boot into Recovery mode
  2. Select Disk Utility from the options
  3. Choose your startup disk on the left sidebar
  4. Click First Aid and then Run to check for errors
  5. If any errors are found, click Repair Disk to fix

First Aid verifies and repairs any directory issues or disk corruption. This can resolve any underlying disk problems interfering with installation.

5. Start in Safe Mode & Disable Extensions

Booting into Safe Mode and disabling third-party extensions can help isolate software issues.

  1. Restart Mac and immediately press/hold Shift key
  2. This boots into Safe Mode with extensions off
  3. Try macOS installation in Safe Mode
  4. If successful, problem may be related to a login item or extension
  5. Restart back into normal macOS
  6. Go to System Preferences > Users & Groups and select Login Items
  7. Delete any third-party apps/extensions
  8. Try installation again normally

With extensions disabled, you have isolated the issue to a software conflict. Removing problematic login items can allow installation to proceed.

6. Create a New Admin User Account

An existing user account issue could also be interfering with system changes needed for installation. Creating a brand new admin account can help rule this out.

  1. Restart Mac and go to System Preferences > Users & Groups
  2. Unlock padlock icon if necessary
  3. Click + to create a new admin account
  4. Sign out and sign in to new account
  5. Attempt macOS installation on this fresh account

If the installation succeeds on the new account, you know the previous user files or settings were causing a conflict.

7. Erase and Format the Startup Disk

For more serious startup disk errors or file system damage that prevent installation, formatting and erasing the drive may be required. This will wipe the disk and create a clean macOS partition.

Warning: This will erase all data and files on the startup disk, so be sure to have backups!

  1. Boot to Recovery Mode by restarting Mac and holding Command + R
  2. Open Disk Utility
  3. Select your startup disk and click Erase at the top
  4. Choose APFS format and GUID Partition Map
  5. Provide a name like “Macintosh HD”
  6. Click Erase to wipe – this may take awhile
  7. When done, quit Disk Utility and install macOS
  8. The clean disk should allow macOS installation now

If you had to erase your startup disk, you will need to restore your data from backups after installation completes.

8. Use a USB Installer Drive

Another option is to create a bootable USB installer drive for macOS. This provides a clean installation source.

  1. Get a 16GB or larger USB flash drive
  2. Plug into Mac and launch App Store
  3. Search for desired macOS version (Monterey, Big Sur, etc)
  4. Download the installer (may take a while)
  5. When done, open Finder and Applications folder
  6. Find and right click on the installer app
  7. Choose Show Package Contents
  8. Open Contents > Resources folder
  9. Drag InstallESD.dmg file to desktop
  10. Plug in prepared USB drive
  11. Launch Disk Utility and select USB drive
  12. Click Erase to format drive
  13. Name it Untitled and choose APFS and GUID format
  14. Click Erase when ready
  15. With USB drive still selected, click Restore tab
  16. Drag InstallESD.dmg file from desktop to Source field
  17. Click Restore – this copies installer files
  18. Boot Mac from USB drive and launch installation

Creating a bootable installer bypasses any corruption in your current macOS and provides fresh files. This can help the installation go through successfully.

9. Contact Apple Support

If you still cannot get past the “installation failed” issue after trying these steps, you may need to contact Apple support directly for further assistance. Have your Mac model details, macOS version you’re installing, and details of any error messages ready.

Some additional options Apple may suggest are:

  • Try installing again via macOS Recovery
  • Perform an SMC reset on Mac
  • Review installation logs for clues
  • Repair or replace any damaged hardware components
  • Schedule a Genius Bar appointment

Contacting Apple Support provides you with professional troubleshooting help. They can walk you through specialized tools and diagnostics to resolve the issue.


While the “macOS could not be installed” error message is frustrating, there are numerous troubleshooting tactics you can attempt to get past it. Checking hardware compatibility, freeing up disk space, using Safe Boot and recovery options, and contacting Apple can all help track down and correct the underlying problem stopping your macOS installation from completing successfully. With patience and determination, you should be able to get the latest macOS version running on your Mac.

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