Installing a new version of macOS can sometimes be tricky, especially if you are trying to install an older version of the operating system. There may be times when you need to do a “force install” to bypass certain checks done by the macOS installer. Here are some tips on how to force install macOS X.
What Does “Force Install” Mean?
A force install of macOS means installing it in a way that overrides the normal installation safeguards. When you try to install macOS normally, the installer checks to make sure:
- The Mac model is supported by the version of macOS you are installing
- There is enough storage space available
- Firmware is up-to-date
If any of these checks fail, the installation will be blocked. A force install ignores these checks and attempts the installation anyway. This allows you to install versions of macOS that are older than what Apple says your Mac supports, or to install on a Mac with outdated firmware.
When Would You Need To Force Install?
Here are some examples of when a force install may be required:
- Installing Mojave on a Mac released after Mojave – Mojave was released in 2018, so if you have a Mac from 2019-2022, a normal install of Mojave would fail. A force install would override the system check and let you install the older OS.
- Downgrading to an older version of macOS – If you upgrade to a newer macOS version and want to go back to the previous one, a force install would be needed since the OS considers it a “downgrade”.
- Installing on non-Apple internal SSDs – The macOS installer wants to make sure there is Apple firmware on the built-in drive before installing. A force install would bypass this check.
- Installing on Macs with outdated firmware – Usually the installer checks for the firmware to be up-to-date before proceeding. A force install ignores this.
In general, any time the macOS installer gives you an error message that your Mac cannot install that version of macOS, a force install attempt may be your only option.
How To Force Install macOS
The key to forcing an installation of macOS is to boot from an external drive rather than your normal startup disk. This allows you to bypass the system integrity checks and other safeguards that happen at boot and installation.
What You’ll Need
- A USB flash drive or other external drive large enough to hold the macOS installer.
- A downloaded installer for the version of macOS you want. Get this from the App Store or Apple’s website.
- The createinstallmedia command line tool. This is on all Macs already, in /Applications/Utilities/.
1. Create Bootable macOS Installer Drive
Use the createinstallmedia tool to format your USB drive and make it bootable. Here is the basic command:
sudo /Applications/Install\ macOS\ Catalina.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume
Replace “Catalina” with the version you are installing, and “MyVolume” with the name of your USB drive.
2. Start Up From macOS Installer USB
Reboot your Mac and hold down the Option key. This will bring up the startup manager. Select your installer USB drive to boot from it.
3. Open Terminal
Once booted to the installer, open Terminal from the Utilities menu in the menu bar.
4. Enter Force Install Command
In Terminal, enter this command:
sudo /Applications/Install\ macOS\ Catalina.app/Contents/Resources/startosinstall --agreetolicense --force
Again replace “Catalina” with your macOS version. This will begin the installation, bypassing checks.
5. Install as Normal
Follow the rest of the installer screens as normal. The OS will be force installed once completed.
Other Force Install Methods
There are a couple other approaches to force installing macOS as well:
Option-Command-R Recovery Boot
Hold down Option-Command-R while booting to start up to online recovery. This boots a recovery system from Apple’s servers instead of your internal drive. You can then force install macOS from there.
Apple Configurator
Apple Configurator 2 is an app for Mac that lets you re-image and configure devices. You can force MacOS installs on Macs using this tool as well.
Risks and Dangers
While a force install can be useful in certain situations, there are some risks involved:
- Incompatible Mac models may have missing drivers, leading to issues.
- Older macOS versions get less security updates over time.
- Could lead to overall system instability or data loss.
- Voids any Apple warranty and support.
Always back up your data before attempting any kind of force install. Be prepared to erase and reinstall macOS from scratch if things go wrong.
When to Avoid Force Installing
Here are some cases where you should avoid force installing macOS:
- Primary work computer holding critical data – Too risky.
- Hardware is very new – Lack of driver support can cause issues.
- Trying to install unsupported major OS versions – Like installing macOS 10.13 on a new M1 Mac.
- Only reason is for testing or novelty – Not worth potential downsides.
In general, only use force installs out of necessity for older Macs that can’t update normally.
Summary
Force installing macOS can be a handy trick for certain situations like installing older macOS versions on incompatible Macs. But it also carries significant risks of system problems or instability. Approach with caution:
- Always backup first
- Make full system clone if possible
- Use on secondary test Macs preferred
- Be ready to clean reinstall if required
With proper precautions, a force install can open up options for older Macs. But avoid on critical systems or Macs with important data.
FAQ
Is force installing macOS illegal?
No, force installing macOS is not illegal, but it does go against Apple’s end user licensing terms. Apple expressly states you should only install on supported hardware. So force installing is technically a violation, but not an illegal act.
Does force install wipe your hard drive?
A force install alone does not wipe or erase your hard drive. However, it is possible for the install process to fail in a way that corrupts your data and requires full reformatting of the drive before successfully installing macOS.
Can you force install older macOS on M1 Macs?
It is generally not possible to install macOS versions older than Big Sur on M1 Macs. The hardware and architecture is so different that drivers will be missing. Attempting so could result in bricking the Mac. Stick to Big Sur or newer on M1.
Is Internet recovery the same as force install?
Booting to macOS Internet Recovery does allow you to get around some checks, but is not as complete in ignoring restrictions as a USB force install. It may work for some scenarios, but a full force install gives you most control.
Can I force install without USB drive?
Creating a bootable USB installer drive is the easiest way to force install. You technically can try booting from network or other disks, but USB gives you the most reliable process. The USB installer drive lets you have the files and tools needed at boot.
Conclusion
Force installing macOS lets you get around the system restrictions and compatibility checks that normally prevent installing unsupported configurations. This guide has covered the general process of how to perform a force install from a USB boot drive in order to install versions of macOS that your Mac would normally reject.
While a force install gives you more control over the OS on your Mac, it also comes with substantial risk of problems. You should only force install if you have already exhausted all other options and have full data backups. When done carefully and selectively on the right hardware, a force install can be a useful technique to prolong the life of older Apple devices.