An error occurred preparing the software update - Big Sur

Hi , these tips were very helpful as I seem to be in the same position. Thank you for this. Although I’m stuck at the point where you mention running “macintosh HD” by clicking run on the top left menu. I can’t seem to find the menu or button you are talking about.

if you were able to elaborate that would be amazing thank you

Hello, I have the same issue as akl_17, but didn't wanted to unmount or erase anything without being 100% sure that I won't be loossing my computer data that is not back up.

Can I do a backup at this point?

Thank u so much.

Denise.

While I was on apple support, they told me to shutdown the computer.

Then they told me to press cmd+control+r while I turn it on again. After 5 or so minutes I was at a screen that told me to login but the computer wouldn't let me login and was telling me that I entered an incorrect password.

So apple support basically told me that I had to

1) try to connect your macbook to another computer and try to keep some of your data

2) erase all the data and go from there.

So I'll be going to the apple store tomorrow and see what happens but It is not looking good for me.

Couldn't boot via safe mode. Finally, I resorted to recovery, but I had to erase contents of my disk first, and then continue the installation of Big Sur. Apparently the low storage space I had left really caused the problem. Now I'm in the process of reinstalling apps and catching up with my relevant files (no Time Machine backup, so...)

Thanks.

Interesting. Having a backup of your data plus a usb stick of macOS so one could boot off it I feel is a good idea.

I feel if one has a backup they can erase the drive if they are unable to reinstall macOS and then restore from back up and then reinstall Big Sur once they have enough disk space.

Hi, I know you posed this a while ago but I’m having the same identical issue and I have no idea what to do. I have tried the control R method, and even the advanced (shift, option, command,R) recovery method. I would love to know what you did to recover your computer, as I am struggling with it and depend on My computer for school.

Hi LizethBo,

Thanks for getting back to me. That's interesting, I assume there is no way to get around the login window and assume you are entering your password correctly for the correct user?

I would try again and see what happens. Based on this will provide you further steps.

What Mac model do you have?

Hope this helps.

Well I finally got mines fix, but I had to erase everything on my computer. I contacted Apple and that was the only way to make my computer work again. It was like I just bought it Everything was lost, but when I downloaded all the apps again everything that I did was there.

That’s what I was going to recommend next, wipe the drive.

it’s always good to have a backup if something like this happens so you could restore your data. Hope you didn’t loose a whole lot though. I remember loosing everything once so know how it feels.

what version of macOS are you running? Do you plan to upgrade to Big Sur, I’d recommend upgrading to Catalina if you can as that’s a good and stable operating system.

I had same problem + ( no recovery mode according to password failure + no safe boot + prohibit sign when I try log in to MAC HD by option key startup)

last night I downloaded big sur and leave my macbook pro 2013 to update.

Today I woke up and lose access to everything. I'm computer student and have many deadlines and projects. I see 640 people had same problem but apple support have not even make official thread or blog page for this problem, and guess what you don't deserve support contact if you are not in US.

I erased my mac, it started in recovery mode. it installed Mojave. It loads successfully. And currently I'm waiting to restore my 2month old backup.

seriously make backups before updating, there's no actual support.

hello, has the same issue as other guy reported.

"I had same problem + ( no recovery mode according to password failure + no safe boot + prohibit sign when I try log in to MAC HD by option key startup)"

Password locked me out and iCloud also not working (both Command + R recovery and Option + Command + R recovery).

I encountered the same error. This appeared because of the lack of space on my Mac, so I had to buy two external HDDs. To one HDD I had to install the Big Sur, to the other I could save all my data in TimeMachine. After that I could erase all data from the computer, install the Big Sur and set back everything from Time Machine. I hope this helps you as well.

I am experiencing the same exact problem like you are (account password failure + prohibit sign + iCloud could not unlock this volume).

I also lost all of my files and I need it for my school.

How are you restoring your data? I need some guidance here.

Hi nóra208,

Thanks for the update. If there is lack of space wouldn't the installer catch that before the install starts and say not enough disk space and prevent the install from happening? For example when you open Install MacOS Big Sur installer in the applications folder in the past it would state you don't have enough space for installation.

I assume you were able to get back into your operating system in order to do a time machine backup?

Glad you were able to save your data as a time machine back up and restore from that.

Hi Soren Pearson, thanks for getting back to me! All of this is helpful!

I think it is too late for me to do the steps you described above because I have reinstalled the stock OS (El Capitan) in result of panicking.

I don't have a time machine backup at all and I know I should have did that before upgrading so now I know. But before I reinstalled the stock OS, I partitioned my hard drive because I didn't see the "Macintosh HD" drive. Do you think this caused my data to be erased completely? What would you do to restore data in this case?