Make a bootable Big Sur USB Installer

[tywebb13]

BETA 1

To make the bootable usb installer for the first beta of Big Sur, once downloaded to the Applications folder format a 16GB USB as HFS+ Journaled, call it Untitled and run this command in Terminal:

sudo /Applications/Install\ macOS\ Beta.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled

You can then boot up with option key and select the bootable usb.

The Software Update preference pane says the first beta is macos 10.16. But when it installs it becomes 11.0.

No name or number is on the installer app for the first beta - which is unusual - previous beta 1's had a number but no name till beta 2. I think the whole 11.0 vs. 10.16 thing had a lot to do with this.

BETA 2 and subsequent pre-release betas - up till Release Candidate 1

The Beta 2 full installer may get a name in which case the command will change too, maybe to

sudo /Applications/Install\ macOS\ Big\ Sur\ Beta.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled

EDIT: This is indeed the command for beta 2.

It will be the command for all the betas until public release or gm release (although apple has previously called the gm a "beta", they may still call big sur gm a "beta" but remove the name "beta" from the installer name - this happened before causing much confusion)

PUBLIC RELEASE and Release Candidate 2

Anyway Release Candidate 2 and public release are the following:

sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled

 

[kkluth]

Thank you for the proper command to create USB.

 

[ssn637]

I am unable to perform a clean installation of macOS Big Sur Beta from the bootable USB flash disk created using the Terminal command given.
MacBook Pro 13" 2018
Switzerland
In preparation for the clean installation, I formatted the SSD as an APFS volume.
After a reboot with the Option key selected, I am able to select the Beta installer, but almost immediately a pop-up message appears claiming the USB disk needs to be updated, which after some movement of the progress bar is unsuccessful, prompting a "Try again" request.
If I then reboot, the computer immediately enters internet recovery mode, but again after a few minutes of movement of the progress bar, an exclamation mark is displayed and I can't go any further. I am also unable to boot into recovery mode via CMD + R. My only option at that point is to reinstall macOS Catalina from a separate USB flash disk.

 

[tywebb13]

I am unable to ...

Well that is strange. I was able to successfully install Big Sur with the bootable usb.

Even apple recommend making the bootable usb in the seed note under certain circumstances:

"You might be unable to install macOS Big Sur 11 beta onto additional volumes. (63677460, 64445236) Workaround: Create a bootable installer using the createinstallmedia command."

So clearly apple are letting you know that the bootable usb should work for this beta.

 

[ssn637]

Update: I upgraded my macOS Catalina to Big Sur, then booted from the USB flash disk and was then able to format the system volume and perform a clean installation.

 

[Jas-Singh685]

@ssn637 Have you checked in your normal recovery mode, that booting from external devices is allowed? Are you unable to boot into your normal OS at all?

Edit: Just saw your update, sorry! Glad you got it sorted, thanks for the update.

 

[tharitm]

Thank you for this, I want to know is there a way to make it a image instead to a physical USB? I'm trying to install it on a VM.

 

[Jas-Singh685]

So I'm having issues installing from USB. I created it successfully using the provided method. But when I actually try to boot, I am greeted by the "A software update is required to use this startup disk"

I continue, confirming the WiFi connection, but it always fails. I have checked "Allow booting from external devices" and "No security" just for the install. But I still get this message. I'm using a 13" 2020 MacBook Pro with the T2 security

Has anyone come across this issue? I'd rather not upgrade my main OS as per the workaround from @ssn637. It seems strange that I can't boot into a bootable USB installer, are clean installs not possible with these T2 Macs?

 

[MrVanosh]

Same issue like Jas-Singh685 on 13" 2019 MacBook Pro. I can't even upgrade from install app because it needs 50GB free space on drive when I can't delete more on my 128GB SSD...

 

[aeternitas]

I upgraded Catalina to Big Sur. My experience with past Betas is that with a clean install sometimes once you install apps they may not work. With an upgrade those apps that you already had installed generally work. This is just my experience. I will perform a clean install once the final version gets released in September.

 

[faranRED]

So I'm having issues installing from USB. I created it successfully using the provided method. But when I actually try to boot, I am greeted by the "A software update is required to use this startup disk"

I continue, confirming the WiFi connection, but it always fails. I have checked "Allow booting from external devices" and "No security" just for the install. But I still get this message. I'm using a 13" 2020 MacBook Pro with the T2 security

Has anyone come across this issue? I'd rather not upgrade my main OS as per the workaround from @ssn637. It seems strange that I can't boot into a bootable USB installer, are clean installs not possible with these T2 Macs?

Try selecting startup disk from system preferences.

@MrVanosh maybe my method can help you too.

 

[MrVanosh]

Try selecting startup disk from system preferences.

@MrVanosh maybe my method can help you too.

It makes no difference, first try installing I booted via selecting usb in startup disk and this error occurred and then I tried with option key to select and also same error :/

 

[faranRED]

It makes no difference, first try installing I booted via selecting usb in startup disk and this error occurred and then I tried with option key to select and also same error :/

Are you by any chance on Catalina ? I too had this problem yesterday and booting from USB threw the same “update required” error. Fed up I just made a new APFS partition and installed Big Sur on it.
Changing startup disk from system preferences is something I just remembered and was successful in booting from USB.
Bottomline, maybe installing macOS Beta fixed something in boot up process that has been screwed in Catalina

 

[Jas-Singh685]

Indeed I am on Catalina and like MrVanosh, selecting it as a startup disk didn't help, maybe it's some kind of compatibility bug? I think I'll end up doing just that, creating a separate partition on my internal SSD and installing to that from the install app.

@MrVanos Perhaps you could install to an external device in the meantime? That way it won't use your internal storage and you don't have your daily partition messed with, and you can use the normal installer app without screwing around trying to get this USB to boot, I have given up with that method!

 

[tywebb13]

Putting things together there are questions about successes and failures which leads me to a theory about why it works for some and not for others - and also leads me to suggest a way to fix it if it doesn’t work.

1. Why did it work for ssn637, but only after upgrading from Catalina to Big Sur - who has a 2018 mbp - one with touchbar - requiring bridgeos update?

2. Why did it work for me without upgrading from Catalina - I have a 2015 mba - without touchbar - so I don’t need bridgeos?

Why my interest in bridgeos? ……. Because that is the ONLY other software so far associated with Big Sur.

So the theory goes like this: If you need bridgeos, upgrading from catalina to big sur will do it for you - and only then will the bootable usb work - because this will install the bridgeos update.

It seems that if you don’t need bridgeos then the usb will work regardless.

So where to get the BridgeOS software packages associated with Big Sur?

Right here of course:

http://swcdn.apple.com/content/downloads/04/28/001-18400-A_9PR1LXEKFC/czmgv59ffn8j0u96xf2tu7tiu2ykcp3izt/BridgeOSBrain.pkg

http://swcdn.apple.com/content/downloads/04/28/001-18400-A_9PR1LXEKFC/czmgv59ffn8j0u96xf2tu7tiu2ykcp3izt/BridgeOSUpdateCustomer.pkg

Maybe if you need BridgeOS you could try installing this before using the USB.

 

[Jas-Singh685]

This is definitely interesting^

Unfortunately, both these packages return an error for me, "This package is incompatible with the version of macOS"...

 

[iWilliamsJ]

To make the bootable usb installer for the first beta of Big Sur, once downloaded to the Applications folder format a 16GB USB as HFS+ Journaled, call it Untitled and run this command in Terminal:

sudo /Applications/Install\ macOS\ Beta.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled

You can then boot up with option key and select the bootable usb.

The Software Update preference pane says the first beta is macos 10.16. But when it installs it becomes 11.0.

No name or number is on the installer app for the first beta - which is unusual - previous beta 1's had a number but no name till beta 2.

The Beta 2 full installer may get a name in which case the command will change too, maybe to

sudo /Applications/Install\ macOS\ Big\ Sur\ Beta.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled

Thank you for this, Will install this on a Samsung X5 for testing purposes the command worked as intended.

 

[vickysud]

This is the error im getting when i instal from USB " An error occurred while copying the update"

 

[4sallypat]

To make the bootable usb installer for the first beta of Big Sur, once downloaded to the Applications folder format a 16GB USB as HFS+ Journaled, call it Untitled and run this command in Terminal:

sudo /Applications/Install\ macOS\ Beta.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled

You can then boot up with option key and select the bootable usb.

The Software Update preference pane says the first beta is macos 10.16. But when it installs it becomes 11.0.

No name or number is on the installer app for the first beta - which is unusual - previous beta 1's had a number but no name till beta 2.

The Beta 2 full installer may get a name in which case the command will change too, maybe to

sudo /Applications/Install\ macOS\ Big\ Sur\ Beta.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled

Thanks for this!
I just made a bootable Big Sur SD card!

 

[bige12]

how long it take to copy the files to make the bootable installer?

 

[MrVanosh]

I reinstalled Catalina to have fresh install with free space to update to Big Sur but I can't even update from existing OS cuz installer can't update bridgeOS for T2 chip I attach logs.

 

[longtom]

@bige12 About 10 minutes for me.

 

[4sallypat]

how long it take to copy the files to make the bootable installer?

Mine took about 6 minutes onto a SD card but then I have a 1Gbps data link....

 

[Jas-Singh685]

I reinstalled Catalina to have fresh install with free space to update to Big Sur but I can't even update from existing OS cuz installer can't update bridgeOS for T2 chip I attach logs.

Did this happen during the normal installer app from within Catalina? The update went smoothly for me, managed to install onto my internal drive with a separate partition. The installer updated my BridgeOS automatically

 

[DeadeyeM]

Why are you guys doing clean install from USB drive when you could do this from Recovery after you done update Catalina > BS ?