How To Install macOS Sequoia On An Unsupported Mac? [Step-Wise]

With each release of macOS, however, Apple drops support to some old hardware yearly, making these so-called old Mac models unsupported by macOS Sequoia officially. Suppose you got a Mac shipped many years ago and are still curious about macOS Sequoia, you can read this article, which explores how to install macOS Sequoia on an unsupported Mac with an elaborate and step-wise guideline.

How to install macOS Sequoia on unsupported Macs:

Preparations

Before the macOS installation, there are some requirements that you need to complete:

• A working internet connection
• A 16GB or larger USB flash drive
• A Mac running macOS Mojave or later

Except for these basic preparations, two more preconditions deserve your great concern here: 

Preparation 1: Completely back up your Mac

Unlike installing macOS Sequoia on a supported Mac, installing macOS Sequoia on an old Mac will wipe the Mac, leaving you no files or folders. For a chance to roll back to macOS Sonoma or a backup against data loss, it's highly suggested to back up your Mac thoroughly.

You can enable iBoysoft DiskGeeker to clone the whole startup disk to external storage as the backup, including the system files, settings, apps, etc. accumulated on the source hard disk.

Preparation 2: Check if the storage is enough to install macOS Sequoia

Many users get stuck in the macOS Sequoia installation by a message saying "Your disk does not have enough free space. Updating requires 14.7 GB of disk space." which infers that there is not enough space to install macOS Sequoia on your Mac.

To avoid such trouble, you'd better check the available storage on your hard drive. 14.7 GB of space size is an absolute minimum while 30GB is better for smooth performance and user experience.

Go to Apple Menu > About This Mac > Storage to see how much available space is left. If it is about or less than 14.7 GB, you're recommended to free up Macintosh HD for more available space with iBoysoft DiskGeeker's clean junk feature immediately!

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Install macOS Sequoia on unsupported Macs in progress

This section is quite essential in the whole installation process, so please strictly follow this guideline for a smooth installation! With such a step-wise tutorial, we believe you can handle this macOS 15 Sequoia install on unsupported Macs with ease!

Step 1: Download the macOS Sequoia installer

You can click here to download the macOS Sequoia installer, which is identical to the one that you dowload from the App Store on supported Macs. 

Preferentially choose the latest version of the InstallAssistant.pkg which is more stable and developed than the older one.

Once the download finishes, please install the pkg file and find the Install macOS 15.app on your Mac with Spotlight Search or Launchpad.

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Step 2: Create the macOS Sequoia bootable USB

Fetch the USB hard drive you prepared and ensure you have backed up everything well, or the following procedure will wipe files on the drive. To smooth the following bootable USB creation, we suggest you reformat the USB drive to APFS file format on your Mac.

1. Open Disk Utility and select the target USB hard drive from the left sidebar of Disk Utility.

2. Click Erase on the top menu bar, give the drive a name, or just leave it original, select APFS in the Format section, and click Erase to begin the reformat.

Once the USB drive is formatted to APFS - a file system fully compatible with macOS, we can begin to create the USB a macOS Sequoia bootable drive.

1. Launch Mac Terminal on your machine and type in the following command line:

sudo /Applications/Install\ macOS\ Sequoia.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume

Remember to replace "MyVolume" with your USB drive name and click Enter to execute the command line in Terminal.

2. Follow the onscreen wizard to complete the bootable USB creation mission. When the Terminal notifies you that the process is done, the macOS Sequoia bootable USB drive is created successfully.

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Step 3: Install OpenCore Legacy Patcher

In this section, we are gonna install the OpenCore Legacy Patcher and prepare for booting macOS Sequoia on your unsupported Mac computer.

1. Go to the OpenCore Legacy Patcher on GitHub and click the Getting Started button to download and install this software on your machine. Or you can click here to download OpenCore Legacy Patcher directly if you have no interest in the basic introduction of OCLP.

2. Once the installation finishes, you can open it to detect your Mac model. For an accurate result, you're recommended to select the target Mac model identifier by yourself.

If you're uncertain about the target Mac model identifier, go to the target Mac's Apple Menu > About This Mac > System Report > Model Identifier.

3. Click on the Settings icon and select the target Mac model identifier from the Target Model menu. If you don't plan to debug the installation, disable Verbose, please.

4. Click on Return to the main window and click on Build and Install OpenCore.

5. When the OpenCore Legacy Patcher is built, it will prompt you to view the build log and install OpenCore to the target disk for booting. Click on Install to disk when you're prompted.

6. Click OK to allow the disk access.

7. Select the bootable USB you formatted before. If the USB isn't listed in the popup, click Search for disks again.

8. Select the volume OCLP lists to place the OpenCore Legacy Patcher. In our case, it's disk5s1 - EFI.

8. Several seconds later, it will prompt a window for you to reboot. If you ensure everything is done, click Reboot.

9. Then, you will see the confirmation popup to restart your Mac, just click on Restart to proceed.

Step 4: Install and boot macOS Sequoia on unsupported Mac

1. When your Mac enters the boot screen after the restart, hold down the Option/Alt key on your keyboard to select the EFI Boot entry with the OpenCore icon.

2. Since you have loaded OpenCore, select Install macOS Sequoia on the boot screen.

If your Mac is looping back into the beginning of the setup after the first reboot, turn it off, start it again, and hold Option. This time, select the option with a grey hard disk icon, it can say "macOS Installer" or the name you gave the disk during the installer process. Keep repeating this step after every reboot if necessary.

3. Follow the onscreen wizard to complete the installation and some user settings like language, network, user account, and so on. 

4. When the setup finishes, you're in macOS Sequoia on your unsupported Mac!

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Post macOS Sequoia install on unsupported Macs

This section provides extra info and details after installing macOS Sequoia on your unsupported Macs. To improve your experience of running macOS 15 on your machine, you can have a quick look:

How to boot your unsupported Mac to macOS Sequoia without the USB hard drive?

If you want to boot your Mac into macOS Sequoia without the bootable USB we've made before, you can change the setting with the following steps:

After these steps are done, you can boot your unsupported Mac to macOS Sequoia without the USB drive.

How to boot macOS Sequoia on your unsupported Mac without Boot Picker?

To do this, run the OpenCore Patcher and go to Patcher Settings, then uncheck "Show OpenCore Boot Picker" on the Build tab.

Once you've toggled it off, build your OpenCore EFI again and install it to your desired drive. Now to show the OpenCore selector, you can simply hold down the "ESC" key while clicking on EFI boot, and then you can release the "ESC" key when you see the cursor arrow at the top left.

About the SIP settings

To install macOS Ventura and all newer macOS versions on unsupported Macs, it's a prerequisite to lower the SIP settings.

Go to OpenCore Legacy Patcher > Settings > Security, then check the options in the pic below:

A video guiding to install macOS Sequoia on unsupported Macs

If you're not an audience to text description, you can watch this video below to install macOS Sequoia on your outdated Mac:

Wrap all up

This post is a comprehensive tutorial on how to install macOS Sequoia on an unsupported Mac, which includes the preparation, while-installation, and post-installation sections. 

It walks you through manually installing macOS Sequoia on your canceled Mac model with step-wise guidance so that you can handle this mission even if you're new to it. If you want to run macOS Sequoia yet have no supported device, try this post right now!

Note that you probably cannot experience every essence and highlight of macOS Sequoia since the outdated hardware is not fully compatible with macOS Sequoia.

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