Unable to create bootable drive for MacBook Air M1

While you tried to be specific, I got lost in exactly what you are doing here because you just mentioned USB boot drive. I don't know which drive(s) are a full macOS drive and which are just a macOS installer. This is very critical information to have and I cannot follow what you have done.

You can use a bootable macOS 11.x+ USB installer on both Intel Macs and M-series Macs.

You cannot move an external full macOS USB drive between Intel and M-series Macs. I'm not even sure you can move an external full macOS boot drive from one M-series Mac to another M-series Mac. I am fairly sure there are some limitations due to the new concept of "Ownership" employed by the M-series Macs. I have not had the time to fully explore external full macOS boot drives on M-series Macs.

Have you actually created a bootable macOS USB installer using the instructions in the following Apple article using a compatible Mac (meaning one that is compatible with the OS you are trying to create)?

Create a bootable installer for macOS - Apple Support

You should also provide the exact models of any Macs you are using here so that we can confirm they are compatible with what you are trying to achieve. Please specify exactly which computer is the one needing to have macOS reinstalled & which one(s) are being used to create a USB installer. You can get the exact models by clicking the Apple menu and selecting "About This Mac", or if the Mac is not bootable, then entering the system serial number on the check coverage page here (please don't post the serial numbers on this forum since they are considered personal information):

Check Your Service and Support Coverage - Apple Support

Plus, please make clear what external drives you are using here. Is the SanDisk Extreme 1TB to be used for a full macOS installation or just to be used for the macOS USB installer?

FYI, the USB drive used for the macOS USB installer must be partitioned & formatted as GUID partition and MacOS Extended (Journaled). This is why you received the one error about APFS not being allowed for bootable install media.

It also seems your iMac running Sierra/High Sierra may be too old to even be used for downloading macOS Big Sur. If you want to create a bootable macOS 11.x Big Sur USB installer, then you generally need access to another Mac from 2013 to 2020.

If you are trying to reinstall macOS to a MacBook Air M1 laptop, then you can try booting into Recovery Mode to reinstall macOS. I really don't know which version of macOS this will give you on an M-series Mac since I haven't really paid attention to how it works. You must access the Startup Options menu by holding down the power button for about 10 seconds on an M-series Mac and select "Options":

How to reinstall macOS - Apple Support

If you cannot use Recovery Mode to reinstall macOS on the M1 laptop, then you will need access to another Mac in order to perform a DFU firmware Revive, otherwise you will more likely need to perform a DFU firmware Restore instead which resets the security enclave chip & system firmware as well as pushing a clean copy of macOS onto the internal SSD.

How to revive or restore Mac firmware - Apple Support

MCabZ wrote:

"FYI, the USB drive used for the macOS USB installer must be partitioned & formatted as GUID partition and MacOS Extended (Journaled). This is why you received the one error about APFS not being allowed for bootable install media." This is really confusing, I have seen various recommendations that the drive should be formatted as APFS/GUID. On an iMac Pro/Sonoma 14.4 The error message I got via the terminal installation process " APFS disks may not be used as bootable install media. An error occurred erasing the disk." I assumed was due to using an Intel Mac for the installation. Can this be the case?

No. The problem here is you are not distinguishing between the drive used for the USB installer and the drive you intend to hold the full OS installation when everything is said and done. The bootable installer and the bootable full installation of macOS are two completely different things with completely different needs for their file systems. The error messages you received & posted here seem pretty clear to me. The information in your post, however, is not very clear such as:

This is really confusing, I have seen various recommendations that the drive should be formatted as APFS/GUID.

The confusing part here is which "drive" you mean here since there are two drives involved when reinstalling macOS using a USB installer. Like I said you need to be very clear to avoid confusion. Any instructions for using APFS/GUID is for the drive that will ultimately end up with the full installation of macOS. However, you then go on to talk about creating the bootable macOS USB installer without actually mentioning the installer although it is implied by mention of the Terminal and the error message you quote.

Here is an Apple article with instructions for creating a bootable macOS USB installer and is the only guide needed for creating a bootable macOS USB installer (I provided a link in my last post as well):

Create a bootable installer for macOS - Apple Support

Yes, I am trying to install Big Sur on the SanDisk Extreme to be used as a boot disk option. The MacBook Air A2338 currently has Big Sur installed, so no OSX incompatibility issues involved.

I'm going to interpret this as the SanDisk Extreme will contain a full macOS installation of Big Sur when all is said & done. If so, then you need to erase the San Disk Extreme as GUID partition and APFS (top option) prior to being able to select it as a destination for the full Big Sur OS installation.

MCabZ wrote:

Thanks for your clarifications. OK, getting clear about my confusion regarding the formatting of the SanDisk. I formatted it correctly APFS+GUID. This is the drive I want to install a full version of BigSur.

Good.

When trying to install BigSur on the SanDisk on an iMac Pro/Sonoma 14.4 The error message I got via the terminal installation process was" APFS disks may not be used as bootable install media. An error occurred erasing the disk."

Why are you using any Terminal commands to install Big Sur onto the SanDisk if it is meant to hold the full Big Sur installation?

Do you have a bootable macOS Big Sur USB installer yet? If not, then create the bootable macOS USB installer using the instructions in the Apple article I linked in my other posts. It is best to use a USB stick for the bootable macOS USB installer.

Once you have successfully created a bootable macOS USB installer, then you just need to Option Boot the Mac by holding down the Option key immediately after hearing the startup chime (Intel Macs only....and you may need to use a wired USB keyboard if you don't get the Option boot screen & Apple boot picker menu). Then you can select the "Install macOS Big Sur" (may say "Reinstall macOS Big Sur) option onto whatever drive you wish as long as it has been properly erased as GUID partition and APFS (top option). If you need to erase the destination drive, then you can use Disk Utility even from the installer to do so before selecting the "Install macOS" option.

Apple has all the instructions needed for the entire process in the Apple article I linked for creating & using a bootable macOS USB installer which I'm linking here once more.....please read it very carefully and follow each step as listed:

Create a bootable installer for macOS - Apple Support

I assume that this error was due to the fact I was using an Intel Mac and not a silicon Mac. Not because the SanDisk was formatted as APFS+GUID.

The macOS USB installers work for both Intel & M-series Macs. The bootable macOS 11.x+ USB installers can be created on either Intel or M-series Macs and used on either type of Mac.

jeffreythefrog wrote:

ok. I've based my thoughts solely based on what I've seen in the community. I do not have anything apple silicon to test it out for myself. so, yes, please come back after you've had time to actually test that theory. I'm quite interested in hearing of your findings. :)

I was finally able to both remember & find some time to experiment while having both a T2 Mac and an M-series Mac available. I can confirm the macOS bootable USB installer can be created using either a compatible Intel or M-series Mac and work on the other system.

I used a MacBook Pro (2018) model and a MacBook Air (M3, 2024) along with the macOS 14.5 Sonoma installer. I created a bootable macOS Sonoma installer using both the Intel Mac and the M-series Mac. The two resulting installers worked on the M-series Mac and Intel Mac. I only tested the ability to boot the installers on the other platform.

AFAIK, the issue is that you are trying to use a bootable installer that was created on an Intel Mac to install macOS on an M1 Mac. that will not work.

HWTech wrote:

The macOS USB installers work for both Intel & M-series Macs. The bootable macOS 11.x+ USB installers can be created on either Intel or M-series Macs and used on either type of Mac.

are you sure about that? I have seen it mentioned many times here that you can only use a bootable installer created on an Intel Mac to install macOS onto an Intel Mac, and vice versa for M series Macs.

jeffreythefrog wrote:

HWTech wrote:

The macOS USB installers work for both Intel & M-series Macs. The bootable macOS 11.x+ USB installers can be created on either Intel or M-series Macs and used on either type of Mac.

are you sure about that? I have seen it mentioned many times here that you can only use a bootable installer created on an Intel Mac to install macOS onto an Intel Mac, and vice versa for M series Macs.

I'm fairly certain I have done so since I've had a M-series Mac since 2020 and have used a Big Sur & Ventura USB installer for Intel Macs, but will try to remember to check tomorrow to confirm....that is if I can find a couple compatible systems for testing. The errors being reported by the OP do not seem related to anything like this from what I can tell.

ok. I've based my thoughts solely based on what I've seen in the community. I do not have anything apple silicon to test it out for myself. so, yes, please come back after you've had time to actually test that theory. I'm quite interested in hearing of your findings. :)

thanks for testing and confirming that. :)