A (relatively) simple guide to create a Bootable MacOS installer USB on Windows

Create a MacOS installer USB (on Windows).md

Create a Bootable MacOS installer USB on Windows

Note! Before proceeding, please make sure that you have a USB flash drive at least 8GB in size. All data will be destroyed on this drive, so please back up your files.

Try this first!

Some awesome guy has made a repo for this exact thing https://github.com/LongQT-sea/macos-iso-builder

Flash resulting DMG with Rufus

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A few comments have mentioned easier ways to make a bootable MacOS USB drive:

this blog post uses UltraDMG and has worked for some (and is easier)

if using this archive.org page people have mentioned after Restore with Disk Image in Step 3, the USB is ready to boot and you can skip straight to Step 4.

Will update this gist soon™

1. Obtaining the image

• Go to this apple.com support article (10.7 Lion - 10.12 Sierra) and scroll down to "Use a web browser for older versions" Right click your desired OS and click "Save link as". Save the DMG to a folder.

• Alternatively, go to this archive.org page for all MacOS images and download your version DMG.

2. Preparing the files

• Using a program such as 7-Zip, open InstallMacOSX.dmg
• If you don't already have 7-Zip, download it from the link above and run the installer.
• Navigate to InstallMacOSX.dmg\Install OS X\InstallMacOSX.pkg\InstallMacOSX.pkg\InstallESD.dmg\OS X Install ESD\
• Extract the BaseSystem.dmg, BaseSystem.chunklist and Packages folder to a folder of your choice
• Now navigate to InstallMacOSX.dmg\Install OS X\InstallMacOSX.pkg\InstallMacOSX.pkg\InstallESD.dmg\OS X Install ESD\BaseSystem.dmg\OS X Base System\Install OS X El Capitan.app\Contents\Resources\ and extract InstallAssistant.icns
• Quit the archiver. We won't be using it anymore.
• In your File Manager (Explorer), rename InstallAssistant.icns to ---> .VolumeIcon.icns

3. Creating the install media

• Download TransMac (Paid software with Trial) and run the installer.
• Insert your desired USB flash drive (8GB+) and run TransMac as Administrator (this will give it the neccessary rights to write to the USB drive.
• Wait 10s! and hit "Run"
• Select your desired USB flash drive and right-click it. Select Format Disk for Mac
• Once finished, right click again, and select Restore with Disk Image
• Select your previously extracted BaseSystem.dmg and hit OK
• Select Enlarge Volume to Drive Size and press OK
• Wait a bit for the files to copy over.
• Select your USB drive in the sidebar of TransMac. There should be a folder called "OS X Base System". Click on the folder.
• The right window pane should show a folder structure
• Go back to your File Manager, and locate and select BaseSystem.dmg, BaseSystem.chunklist and .VolumeIcon.icns
• Drag all 3 files to into the right pane of TransMac. They should begin to copy over.
• Still in TransMac, navigate to USB-Disk\OS X Base System\System\Installation\
• Delete the "Packages" File
• Replace this with the "Packages" Folder that we extracted earlier.
• Wait for the folder to copy over.
• That's it! Eject the USB flash drive and unplug it from your computer.

4. Booting and Installing

• Go over to your Mac. Make sure it is shut down.
• Plug in the USB flash drive we just created.
• While holding the Option (Alt) key, power on your Mac. Keep holding the Option key.
• When you see a menu with your USB flash drive on it, release the key.
• Select OS X Base System and hit Enter
• Follow the installation prompts!

5. Uninstalling and Cleaning (Optional)

• TODO

All credit to: https://www.youtube.com/watch?v=_g8naTAC9jA

Just dropped a quick read on your gist — really solid breakdown . I ran into a similar issue before and what finally saved me was UltraDMG. It made creating a bootable macOS USB on Windows way less painful for me, super straightforward compared to fiddling with command lines. If anyone else here is stuck, that tool was a UltraDMG in my case.

Source:
https://www.sysgeeker.com/blog/how-to-create-macos-monterey-bootable-usb-on-windows-10-11.html

Well, looks like Ultra DMG works as well, I’ll give it a try and update my gist. Thanks for contributing!

Well, looks like Ultra DMG works as well, I’ll give it a try and update my gist. Thanks for contributing!

Hey, did you get around to testing UltraDMG yet?
Just to share — TransMac is paid and honestly pretty expensive (US $59 for a single user license). UltraDMG is way cheaper and does the same thing when it comes to creating macOS bootable USBs.

And from my own experience, on Windows there really isn’t any free tool that can properly make a Mac bootable installer, so it might be worth replacing TransMac to UltraDMG in your gist. That way people don’t assume they need to spend that much just to get it working.

UltraDMG works great on my Windows 11 laptop:

I got an erroring while uploading OS X (A1278; No Osx)

Thank you, so much for sharing!!
I having a hard time figuring out what to do with this laptop since it couldn't seem to connect to Apple's servers.

I had some trouble finding the Packages folder I was supposed to back up (I should have checked the "repacking" part sooner); however, this worked perfectly for me for installing Lion (macOS X 10.7)!

i got the Ø symbol error after i selected OS X Base System and hitting enter. do i need to follow the video you linked?

hi. the dmgs in the archive.org link work perfectly on their own. the files seemed ready to me so i just formatted then restored the download as is.

for reference i chose monterey and plugged it into a macbook air 2017. good luck

Thank you, so much for sharing!! I having a hard time figuring out what to do with this laptop since it couldn't seem to connect to Apple's servers.

I had some trouble finding the Packages folder I was supposed to back up (I should have checked the "repacking" part sooner); however, this worked perfectly for me for installing Lion (macOS X 10.7)!

Hi. I can't still find the Packages folder. How did you find that or what was the workaround?

Thanks!

I can't still find the Packages folder. How did you find that or what was the workaround?

I found it in USB-Disk\OS X Base System\System\Installation\ . I only thought to look there because that's where you are supposed to put the Packages folder on the "edited" DMG.

I can't still find the Packages folder. How did you find that or what was the workaround?

I found it in USB-Disk\OS X Base System\System\Installation\ . I only thought to look there because that's where you are supposed to put the Packages folder on the "edited" DMG.

Thank you, it helped me find it, but it still doesn't work.
When I boot, I am welcomed by the 🛇 icon without any error code or message.

I can guess it's because the hardware is not compatible with the OS I'm trying to install. I was trying to find a workaround, since I can't install OCLP on that machine and can't upgrade past El Capitan.

Will make a new post asking for help I guess.

can't install OCLP on that machine and can't upgrade past El Capitan.

Do you know which OS came on the computer? I would start the process there and update to the version you want.
Unless ... Apple is very controlling. It might be easier to put the "correct" OS on as bases system and then see if you can run others as a VM.

@advixity Suggest updating this guide to use the official DMG installer downloaded directly from Apple’s website via a GitHub Action.

The resulting DMG image can then be flashed to a USB drive using Rufus, the open source software for creating bootable USB drives.

Supports Lion, Mountain Lion, Mavericks, Yosemite, El Capitan, Sierra, High Sierra, Mojave, Catalina, Big Sur, Monterey, Ventura, Sonoma, Sequoia, and Tahoe.

If there is a way to download from an official source, we should use it rather than an untrusted source.

https://github.com/LongQT-sea/macos-iso-builder

Suggest updating to use the official DMG installer downloaded directly from Apple’s website via a GitHub Action.

The resulting DMG image can then be flashed to a USB drive using Rufus, the open source software for creating bootable USB drives.

Supports Lion, Mountain Lion, Mavericks, Yosemite, El Capitan, Sierra, High Sierra, Mojave, Catalina, Big Sur, Monterey, Ventura, Sonoma, Sequoia, and Tahoe.

If there is a way to download from an official source, we should use it rather than an untrusted source.

https://github.com/LongQT-sea/macos-iso-builder

Hi, and thank you for taking yout time into answering me.

Unfortunately, that solution doesn't help me, because I am using a mid 2007 iMac (A1115) and its CPU is not supported by any OS beyond El Capitan, not even by OpenCore.

I had to buy a Penryn CPU (In this case, I bought the model T9500) and replace it. I used this situation to also upgrade the HDD and relace it with an SSD, and I upgraded to its max supported RAM (4GB) and now I am able to use Sequoia flawlessly thanks to OCLP because as I said, I can't update past El Capitan using official methods.

It's been quite an adventure.

@admarty Sadly, those ISO's cannot be used with rufus, as it claims those are unsupported.

@advixity you failed to note that UltraDMG is paid software. Thus it cannot be used unless one buys a license, which is stupid tbh

@Zeldaboy14 You failed at simple reading buddy. The README literally said ISO for virtual machine and DMG for a bootable USB, my comment also said DMG image.

Hello,
I am trying to install el captain on a 2008 MacBook Pro. I get all the way until the installation process where it’s like “x minutes remaining,” then about 30 seconds later I get to here. I click “reset” and the entire screen goes gray. Maybe I messed up somewhere along the way??
Honestly though, I’ve been working to upgrade from No OS to 10.8.5 to 10.11 for 3 weeks now, and this is the farthest I’ve gotten!

Just click restart and wait.

I’ve done that, but now it dosent let me do the process of installing it from the flash drive at all. It just lets me boot 10.11 recovery, which I can’t do anything with.. hm

I can open the flash drive from inside 10.8s OS, but selecting “install OS X El Capitan” just tells me to contact apple support.

Try this https://file.xn--b-tqa.net/api/public/dl/QLTtzEK-/macOS/macOS_installers/macOS_El_Capitan_10.11.6.dmg.img

Plz report back as soon as possible.

hi, it says this when i try to open it..

Write it to USB drive with Rufus, then boot your Mac using that USB drive

Hmm,. It’ll do this and then say that the computer had to shut down because of an error. Maybe I did something wrong in Rufus?

also, thank you for helping me with this project hahaha

THANK YOU SO MUCH!

same issue as the others... I cannot find the Packages folder on Catalina 10.15.dmg.
But I found it in Sierra 10.12.

i’m curious; can you recover an apple silicon macbook with this guide? I feel like this only helps you install a very old macOS version, no?

PERFECT!!! Thank you!

Absolute best tutorial I've found on this.

I'm not sure why anyone here is telling people to use Rufus to create bootable USB drives from .DMG files. If you try to do so, Rufus literally tells you it cannot do it:

Don't worry, people, it's fake news. @djhalnon
Rufus is still working normally with the raw DMG image downloaded from macos-iso-builder.

I'm not sure why anyone here is telling people to use Rufus to create bootable USB drives from .DMG files. If you try to do so, Rufus literally tells you it cannot do it:

You need a raw GPT/MBR disk image (not an APM/Apple Partition Map image) for Rufus to work.