Can't choose Big Sur as startup disk in Catalina and earlier

[iFrez]

Hello! Installation was successful done without any issue. But now (probably after using bootcamp to mount windows drive) my Big Sur drive becomes unmountable.

I have mac mini 2012 late & Big Sur beta 4 installation.

Unusual behaviour: Big Sur drive become writable. I'm trying to make it bootable by using "Modifying the System volume yourself" part of instruction but with no luck.

I still can boot in Catalina and Windows drive as normal. But then i try boot Big Sure i got error "The bless tool was unable to set the current boot disk".

Thanks in advance for help.

[barrykn]

If you're using the Startup Disk control panel in Catalina, that error is normal (at least for now). You need to start from the patched Big Sur installer USB, then go to the Apple menu and choose Startup Disk, and use that version of the Startup Disk control panel to choose the Big Sur installation.

Unfortunately, the earliest macOS version that can choose Big Sur beta 3 or later in Startup Disk... is Big Sur beta 3 or later. (Now that I think about it, I should mention this somewhere in the Readme.) Unless Apple has fixed this in the Catalina 10.15.6 Supplemental Update that came out earlier this week. (Probably not, but it's a possibility, and I haven't had a chance to test it yet.)

[barrykn]

I should check whether this was fixed in Catalina 10.15.7 (it was not fixed in 10.15.6). If not, I might be able to patch the bless command.

[iFrez]

Error exist for me (Catalina 10.15.7)

[barrykn]

Thanks for letting me know.

[bergui45]

same mess for me from Catalina 10.15.7

[bergui45]

I will gladly hear from others having fixed the issue...