Impossible to install (fresh) macOS beta on t2 Macs

Hello, recently I tried to do a fresh install via a USB drive with create install media.

I changed the paths around so that it used the macOS Beta installer and then it wrote the Big Sur installer to the USB.

I booted my MacBook Pro 13" 2015 from this USB drive, and it indeed booted into the macOS Big Sur recovery setup.

However, when I tried this on my brand new 2020 MacBook Pro, it kept booting into internet recovery mode. Yet I had previously enabled "Booting from external volume" and enabled "No security" to allow the installation of unsigned media.

I suspected that it was maybe to do with the fact that I had downloaded the beta installer and wrote it to the USB drive on my OLD MacBook. So what I did was is copy it to a secondary USB drive, boot recovery mode on my NEW MacBook, placed the 2nd usb and original USB into my NEW MacBook, and then ran the create install media from terminal in the recovery mode on the new MacBook.

This seemed to have changed something because I was now able to boot from this Newly written USB. However, upon entering safe mode I would get the message

"An update is required to boot from this volume"

I selected update, my Mac then proceeded to show the Apple logo with the progress bar and after about 3 minutes I was put into recovery. Now I was presented with something along the lines of "There was an error updating"

I pressed Try again, same issue. I rebooted and then re ran the update, same issue.

It seems like it is Impossible to boot the macOS Big Sur installer to perform a clean installation as recommended by the developer notes.

In macOS Catalina recovery, I connected the usb containing the Big Sur.app and then opened terminal, navigated to the volume and then manually launched the app. This worked and showed the beta installer. However, upon selecting my now formatted APFS drive it displayed a blank progress bar and after 10 minutes of nothing I called it off, installed Catalina and updated to Big Sur via Catalina.

Replies

You need the latest BridgeOS update to boot to Big Sur Recovery. Since you are still on an old version, recovery attempts to update it first. The update fails because the Big Sur BridgeOS version is not available or is not working correctly right now.

The only way to perform a fresh install is to upgrade from Catalina (bridgeOS updates to newer version) then you can perform fresh installs.