Reinstalling macOS is often a go-to solution when experiencing problems with your Mac. However, sometimes reinstalling macOS does not work as expected. There are several potential reasons why reinstalling macOS may fail or not complete properly. In this article, we will explore the most common issues that can prevent reinstalling macOS from working and provide troubleshooting tips to help get the reinstall back on track.
Common Reasons Reinstall macOS Fails
Corrupted macOS Installer App
One of the most common reasons a macOS reinstall will fail is a corrupted installer app. The macOS installer is downloaded from the App Store and can become damaged oraltered during the download process. A corrupted installer will often fail right away or during the actual installation with an error message.
To troubleshoot, first trash the installer app and download a fresh copy from the App Store. Be sure to use a reliable Wi-Fi or wired internet connection for the fastest download speed. Also, do not open or modify the installer app after downloading – simply launch it to begin installation.
Insufficient Disk Space
Reinstalling macOS requires at least 12GB of available storage space on the startup drive. If your Mac’s disk is nearly full, it may not have enough room for the full installation to complete.
To check available space, go to Apple menu > About This Mac and look at the Storage tab. Make sure there is at least 15GB free just to be safe. If space is low, delete unused files and apps to free up room before reinstalling.
Incompatible macOS Version
Trying to install an older or newer macOS version that is not designed for your Mac model will result in failure. Check that the installer app is the right OS version for your Mac’s hardware. Reference Apple’s macOS compatibility chart online if unsure.
For example, installing macOS Sierra on a new Mac with an M1 chip will not work. Always aim to install the latest macOS version compatible with your Mac. Downgrading to an older OS can also cause issues.
3rd Party Apps Interfering
Some third party apps, security software, and certain startup items can interfere with the macOS install process. It’s best to boot into Safe Mode before reinstalling macOS to disable other apps and software.
Restart your Mac and hold the Shift key when you hear the startup chime to boot into Safe Mode. This will prevent third party items from loading so the install can run cleanly.
Corrupted Startup Disk
File system errors or disk corruption on the Mac’s boot drive can also block a macOS reinstall from being able to complete. Running First Aid from Disk Utility may resolve these types of issues.
First Aid verifies and repairs directory data structures on the startup disk. To run it, reboot to Recovery Mode, launch Disk Utility, select the startup disk volume, and click First Aid. Allow the repair process to complete, then try the OS reinstall again.
Problems With macOS Recovery Mode
The macOS Recovery environment on your startup disk can become corrupted or damaged. This is required for reinstalling macOS. You may see messages that “macOS could not be installed” or Recovery failing to open the installer app.
To resolve this, you will need to reboot from an external macOS installer on a USB thumb drive or external disk. This will provide a clean macOS Recovery system to run the reinstall from.
Installed RAM Not Meeting Requirements
Apple outlines minimum RAM requirements for each macOS version. If your Mac does not meet the required RAM for the OS being installed, the process may fail or be unstable.
For example, macOS Monterey requires at least 4GB RAM. Check Activity Monitor to view your current RAM installed and make sure it meets the system requirements before reinstalling. Upgrading RAM may be necessary.
How to Repair the Startup Disk Before Reinstalling macOS
Before attempting a macOS reinstall, it’s a good idea to run Disk Utility First Aid on the startup disk to fix disk errors. Here are the steps:
- Restart your Mac into Recovery Mode. Hold down Command + R on boot.
- Select Disk Utility when the macOS Utilities window appears.
- Choose your startup disk volume from the sidebar.
- Click First Aid in the top center and run it.
- Allow First Aid to check and repair any issues with the disk.
- When finished, quit Disk Utility and proceed with the macOS reinstall.
Running First Aid can resolve directory corruption, file system problems, and permissions issues that may interfere with reinstalling macOS.
How to Make a macOS Installer USB Drive
If your Mac is having issues booting to the macOS Recovery environment over the internet, creating a macOS installer on an external USB drive can often resolve this. Here is how to make one:
- Get a 16GB or larger USB thumb drive and connect to your Mac.
- Launch the App Store on your Mac.
- Search for the macOS version you want to install.
- Download the installer app from the App Store.
- Quit the App Store and open Finder.
- Go to Applications and find the installer app you downloaded.
- Right-click or Ctrl-click the installer app and choose Show Package Contents.
- Open Contents then MacOS. Locate the fileInstall macOS.tool.
- Drag install macOS.tool to your USB drive in Finder.
- Allow some time for the file to copy over.
- Rename the USB drive Install macOS [Version].
- Boot from this drive to reinstall macOS.
This will provide a startup disk with the macOS Recovery environment required to complete the fresh installation.
How to Fix “This Copy of the Install macOS Application is Damaged” Error
If you get an error that your Install macOS app is damaged when trying to reinstall macOS, follow these steps to resolve it:
- Quit the installer app if open.
- Go to Finder and delete the Install macOS app.
- Empty Trash to fully remove the damaged installer.
- Go to the App Store and download the installer again.
- Use the new installer app to retry the macOS installation.
- If issues persist, restart and hold Option during boot to select the installer drive.
- Reset NVRAM before installation – Hold Command + Option + P + R on startup and release when you hear the second boot chime.
This will remove the corrupted installer and replace it with a fresh working copy from the App Store. Resetting NVRAM can also resolve issues detecting the correct startup disk for installation.
How to Fix macOS Install Failing Due to Low Disk Space
If your startup disk is low on space, the macOS install may fail partway through and show an error that there is not enough room. Here is how to fix this:
- Quit the installation if in progress.
- Restart to macOS Recovery Mode. Hold Command + R during boot.
- Open Disk Utility from the macOS Utilities window.
- Select your startup disk on the left sidebar.
- Click Erase at the top and choose APFS format.
- Confirm the erase – this will free up space by erasing the drive.
- Quit Disk Utility when finished erasing.
- Restart the macOS installer to retry installation.
Erasing the drive will clear space and allow the full macOS install to complete. Be sure to backup any needed data first before erasing.
Tips for Troubleshooting a Failed macOS Install
Here are some additional tips for troubleshooting and fixing issues when the macOS installation fails:
- Try safe mode – Hold Shift on startup to disable third party software.
- Boot to macOS Recovery online or from a USB drive.
- Wipe and erase the startup disk entirely before reinstalling.
- Reset NVRAM to clear old disk settings – Hold Command + Option + P + R during boot.
- Make sure Date & Time settings are correct in Recovery Mode.
- Check disk health with First Aid in Disk Utility.
- Create a backup before reinstalling in case data is lost.
- Check Apple’s support site for common macOS install errors.
- Try installing the OS more than once if it fails initially.
Following these tips can help isolate where the install issue is occurring. Fully erasing the startup drive before reinstalling is often the most reliable fix for a stubborn failed macOS installation. Backing up data in advance is critical.
When to Contact Apple Support for Assistance
If you still cannot complete the macOS installation after trying the various troubleshooting steps, it may be time to seek assistance from Apple support:
- Persistent errors even after erasing the startup disk, creating a bootable installer drive, and safe mode.
- The install progress bar hangs or freezes partway through installation.
- Mac frequently crashes when trying to install macOS.
- You experience kernel panics during the installation process.
- You erased the startup disk but macOS Recovery still fails to reinstall the OS.
Major errors during installation like frequent crashes, kernel panics, or a stuck progress bar typically indicate a hardware, disk, or software issue needing a deeper diagnosis. Contact Apple or visit an Apple store to have a technician inspect your Mac.
Frequently Asked Questions
Why does my Mac get stuck at 2 minutes remaining when installing macOS?
If the install progress bar hangs at around 2 minutes or less remaining, it is likely due to the macOS installer configuring settings and optimizing apps. Let it continue for 30 minutes or more – it should finish booting up normally after the perceived hang.
How can I get macOS Recovery to work if my startup disk is corrupted?
You will need to create a bootable macOS installer on a USB drive. This provides a working Recovery environment to reinstall the OS when your internal drive is too corrupt to boot to Recovery over the internet.
What should I do if my Mac shows no startup disks available?
This is typically caused by a corrupt NVRAM storing invalid disk data. First reset the NVRAM by holding Command + Option + P + R during startup. Then boot to Recovery Mode and run First Aid on your startup disk. Also reinstall macOS if needed.
Why does my Mac say no packages are eligible for install when reinstalling macOS?
This error can occur when the macOS installer itself is damaged. Delete the installer app, reboot, and download a fresh installer copy from the App Store. Then attempt the reinstallation again.
How can I fix an error that my disk cannot be unlocked to start macOS install?
Go to Disk Utility and make sure your startup disk is mounted and not listed as locked. If locked, click the padlock icon to unlock it so macOS can access the drive. Also check FileVault encryption is disabled.
Conclusion
Reinstalling macOS is a useful troubleshooting step for a misbehaving Mac, but the process does not always go smoothly. Corrupted installers, disk errors, storage space issues, and software conflicts are common culprits behind a failing macOS reinstallation. By methodically isolating the cause and applying the right solution, you can get the OS reinstalled and your Mac back up and running again. Don’t hesitate to contact Apple support if problems persist after trying the standard troubleshooting procedures. With persistence and care, you can successfully refresh your Mac with a brand new macOS install.
