make-macos-15-sequoia-bootable-usb.md

Create macOS 15 Sequoia Bootable USB Free on Mac

macos Sequoia is publicly available for a couple of months. There are a lot of people planning to upgrade to Sequoia. One of the most popular ways to do that is creating a bootable macOS Sequoia bootable USB. In this post, I will show you how to create a macOS 15 Sequoia bootable USB so you can test it out on your Mac.

First, download the macOS Sequoia Install Assistant pkg installer (macOS Sequoia 15.1.1) from this link.

Next, double click the .pkg file to copy the macOS 15 Install App to the Application folder.

Connect a USB drive to Mac and find the usb name with the following command:

ls /Volumes/

Run the followig command to create a bootable USB of macOS Sequoia:

sudo /Applications/Install\ macOS\ Sequoia.app/Contents/Resources/createinstallmedia –volume /Volumes/USB_Volume_Name

This will first erase the USB drive to HFS+ and copy all files and folders to the target USB drive. Once it is done, it makes the USB bootable by writing boot sector to the physical USB.

To boot from Sequoia installer USB on Intel Mac, restart your Mac and hold the Option key. Wait 30 seconds and choose the volume name (Install macOS Sequoia) to start installing Sequoira. For Apple Silicon Mac, power off the device and keep pressing the Power key. This will load startup options where you can see the bootable volume on the screen.

Common Errors When Working the Command

You might come across the following errors when runnng the createinstallmedia command with Install macOS Sequoia Install app:

1. /Applications/Install macOS Sequoia.app does not appear to be a valid OS installer application.

2. An error occured while preparing the installation. Try running this application again.

3. Failed to extract AssetData/boot/Firmware/Manifests/InstallerBoot/* from update bundle The bless of the installer disk failed.

[Alternative Solution for Making Sequoia Bootable USB]

The above trick can be only done on a Mac that fully supports macOS Sequoia. The above command will fail on old Intel Macs and Windows PCs. An alternative way is to download macOS Sequoia bootable dmg file from Google Drive:

https://drive.google.com/file/d/1FsGmfjL3N6prtRoYapO7nt3e7lVB-yGz/view

After that, follow this guide to make a bootable macOS Sequoia USB from the dmg file: https://www.howtogeeker.com/make-macos-bootable-usb-on-any-computer

Does this work on old Mac? I have a Mac running Monterey and needs to confirm if it is able to make a Sequoia bootable USB on my Intel Mac late 2015?

Can I use this bootable usb to install macOS 15 Sequoia on unsupported MacBook Pro? I heard OpenCore Legacy Patcher but not sure it is still working on the latest macOS.

Can I use this bootable usb to install macOS 15 Sequoia on unsupported MacBook Pro? I heard OpenCore Legacy Patcher but not sure it is still working on the latest macOS.

No. You have to patch the installer manually if you are going to install Sequoia on an unsupported Mac.

Does this work on old Mac? I have a Mac running Monterey and needs to confirm if it is able to make a Sequoia bootable USB on my Intel Mac late 2015?

No. You must have a macOS Sequoia compatible Mac to run the command. For old intel mac, the alternative way is to download Sequoia bootable dmg file and flash it to USB drive. By doing this, you will have a bootable USB installer.

1. /Applications/Install macOS Sequoia.app does not appear to be a valid OS installer application.

This was happening to me, because the EFI partition of the USB drive was mounted. Doing sudo umount /Volumes/EFI made the error go away.

That sounds ridiculous, but clearly the installer was "a valid OS installer application", evident by it working now, but also that I had previously removed it and re-downloaded it (softwareupdate --fetch --full-installer-version 15.4).

It had also worked before mounting the EFI partition.