Startup Security Utility, No Administrator found

[asen]

I'm trying to install Big Sur form an external USB flash drive on a MacBook Air from early 2020, but I'm stuck in the Startup Security Utility. When I try to allow booting from an external startup disk, it asks for an Administrator. But there is no such account because the SSD has been completely wiped and there is no OS installed. And Internet Recovery doesn't work either, the installation always fails shortly before finishing, no idea why. Called the Apple Hotline, they told me to try it with a USB stick. Previously Catalina was installed, the problems started when I was trying to upgrade to Big Sur.

I feel like stuck in a loop, anyone has an idea how to get out?

 

[Ronis_BR]

I have exactly the same problem! I am trying the Internet Recovery right now. Could you fix this issue?

 

[asen]

I have exactly the same problem! I am trying the Internet Recovery right now. Could you fix this issue?

Unfortunately not. Apple Support suggested to try Internet Recovery in another network, but it failed again. I guess something is really messed up, so I will send the computer for repair.

 

[Ronis_BR]

I could fix the issue! I started the Internet Recovery (CMD+R) and stayed very close to my router. After two tries, everything worked and I could boot in Catalina. After that, I configured the account, iCloud, etc. With the admin password, I rebooted in recovery again (CMD+R) and removed the restriction to boot from external USB. Then, I tried to install Big Sur from bootable USB, which failed. In this time, it was caused by a problem in my USB-C HUB. I found an adapter USB-A to USB-C for my USB stick and tried to install Big Sur again. This time, everything worked and I could boot correctly in Big Sur.