Big Sur Upgrade: Unable to set startup disk in MacOs Update assistant (SDErrorDomain error 104).

[pastrychef]

Yes, I have a ethernet wire. The Wi-Fi has been turned off. Does that affect? Should I do Wi-Fi only?

Shouldn't matter if you have ethernet connected.

 

[perdja]

Miracles to happen...with a little help. I read the error in post #18 and it indicated that the file "boot" in the root was causing the error. Well, I deleted it and ran yet another upgrade for Big Sur (actually i first made an attempt on Catalina but the result were the same and thought to myself that "maybe it has to do with the Clover update".

So I started a bold Big Sur update instead...and it worked!!

Well more or less. It made all the reboots and then the final 13 minutes with the apple, great suspense...it allowed me to login and I logged in. To Mojave?!!! Yes, thats what met me first. Some dispair and I made a number of reboots from pre-boot, HD-Data (stopped working) and finally HD and Heureka, there it was. Big Sur! There must have been some final consolidation that was not made because the HD-Data partition finally disappeared.

So it seems that root cause was the boot file in root.

All stuff seems to be working, well more or less. However I get the old Preferences when i choose from menu, but I saw that it was a known thing where there are dual Preferences app, so I have to choose the right one by Spotlight search. Also I have to get Audio hijack updater to run. Their "how to allow ACE guideline" does not seem to work. Tried to "sudo spctl --master-disable" to get the Anywhere option in Allow apps in security, but it does not seem to work. Also tried to download OBS Studio 26.1.2 update to handle a known Big Sur issue, but I get an error message opening the dmg ("is damaged and can not be opened) which is strange as i downloaded the exact same dmg to another non Big Sur Mac and launched it without problem.

But apart from that it seems that mission is accomplished. Will see what I stumble on during work activities tomorrow! Good night!

 

[perdja]

Miracles to happen...with a little help. I read the error in post #18 and it indicated that the file "boot" in the root was causing the error. Well, I deleted it and ran yet another upgrade for Big Sur (actually i first made an attempt on Catalina but the result were the same and thought to myself that "maybe it has to do with the Clover update".

So I started a bold Big Sur update instead...and it worked!!

Well not really. The update does not seem complete. Will make another separate post on that.

 

[Karless]

I have the same problem.I installed Big Sur in an external ssd disk and I can’t choose this disk as bootable , I get the same error.any way to fix it?

 

[perdja]

I have the same problem.I installed Big Sur in an external ssd disk and I can’t choose this disk as bootable , I get the same error.any way to fix it?

Well, I don't have any particular advice. From what I read there seems to be several paths to that error message. The only thing I can recommend relating to Big Sur is to make a clean install and use the Migration tool, which worked really nice (almost) as I commented upon here.

As a sidenote, but relating to your scenario with external drive: as I was unsure on behaviour I started the clean installation process with a functional EFI config on an otherwise empty external drive (an M.2 970 card). After successfull Big Sur installation process on that drive I then used migration tool to transfer my user content from the working Mojave install to Big Sur drive. After verifying that everything was OK, I swapped the internally installed M.2 card with the external one.

In essence: I don't think that the fact that you are installing to an external drive is a factor in the error message your are seeing.

 

[Karless]

Well, I don't have any particular advice. From what I read there seems to be several paths to that error message. The only thing I can recommend relating to Big Sur is to make a clean install and use the Migration tool, which worked really nice (almost) as I commented upon here.

As a sidenote, but relating to your scenario with external drive: as I was unsure on behaviour I started the clean installation process with a functional EFI config on an otherwise empty external drive (an M.2 970 card). After successfull Big Sur installation process on that drive I then used migration tool to transfer my user content from the working Mojave install to Big Sur drive. After verifying that everything was OK, I swapped the internally installed M.2 card with the external one.

In essence: I don't think that the fact that you are installing to an external drive is a factor in the error message your are seeing.

Because I can’t set the external ssd as bootable I haven’t finished the installation.Installer promted me to restart my iMac but I can’t set it as startup disk to finish it.

I boot with the default hdd disk which bug Sur is installed but I want a fresh install to my ssd in order to swap it as my main bootable drive.

can mitigation help me ?

 

[perdja]

Because I can’t set the external ssd as bootable I haven’t finished the installation.Installer promted me to restart my iMac but I can’t set it as startup disk to finish it.

I boot with the default hdd disk which bug Sur is installed but I want a fresh install to my ssd in order to swap it as my main bootable drive.

can mitigation help me ?

Well, you seem to be running a non-hack-mac so you should disregard my sidenote and indeed anything I wrote as I can nor vouch for it to be relevant at all for factory macs...