An Error Occurred Preparing The Software Update – Macbook Pro


I am detailing my journey through this update on my Macbook Pro so that it can help others.

an error occurred preparing the software update

2019 MacBook Pro 2.3Ghz, Upgrading from Catalina to Big Sur.

The process…

  1. Big Sur downloads
  2. restarts then tries to install and gets stuck at 10%, giving the error you see below
  3. Trying to start in recovery then asks for your password, which the Mac tells you is incorrect
  4. Trying to enter your vault key from iCloud doesn’t work either because it tells you your “iCloud account cannot unlock this volume
  5. There is no way to get to a main screen or any screen; no way to recover or enter your password for anything
  6. Spent 2 hours on the phone with Mac support: we finally were able to to get it to a Utility screen by pressing “Shift + Option + Command + R” at the same time immediately after hitting the power button, wait a long time for it to start up; where you will see a world icon with a bar or timer under it; took about 15 minutes
  7. In the utility screen settings, when they finally appear after having to re-enter your password for your Mac; and I found out what was wrong; my Macbook didn’t have enough space; you can see in the below screenshots
  8. Big Sur is 13GB. My Macbook Pro had 9.5GB of free space; normally, Big Sur would not have downloaded knowing it didn’t have enough space… but that didn’t happen, so it tried to install itself anyway, and got stuck
  9. Now, there is no way to clear space; the hard drive section in Utilities is missing so we cannot reset the OS (Operating System) to an older version
  10. Apple Support said take it to an authorized Apple Repair shop; so I did
  11. Took it to a Mac specialist locally and they said they have no idea how to fix it; but they would have to wait 3-5 days likely at minimum before Apple released a resolution, also a lot of people are having this issue
  12. You need your laptop for work or school, so this is debilitating, I feel you.

Connecting Your Mac To Another Mac For Recovery

You can try this; but both Macs have to be the same hardware/version.

starting recovery mac to mac

The Supplied iCloud Account Was Unable To Unlock This Version

“If you can’t log in to your computer because you forgot your password, you can reset it now”.  Trying to recover your Mac using your iCloud account will not work either, it just gives you this error message.

the supplied icloud account was unable to unlock this volume

Using MacOS Utilities To Restore from Big Sur Update To Catalina or Earlier Version

  • Time Machine – this only works if you had been saving everything you do on a backup device, like a second hard drive that you attached to the Macbook. If you haven’t been, this is not going to work.
  • Reinstall MacOS – It fails; but if it works it means you lose everything not saved in the cloud or on a backup drive
  • Disk Utility – It is not showing the necessary hard drive in order to clear space or reset the OS (Operating System)

Go to Utility screen by pressing “Shift + Option + Command + R” at the same time immediately after hitting the power button, wait a long time for it to start up; where you will see a world icon with a bar or timer under it; took about 15 minutes and it brings you to this….

macOS utilities not working for recovery big sur

Not Enough Space For The Big Sur Mac Update

So, I finally found out that the reason Big Sur is not installing is that there was barely enough space. However, there is no way now to clear the space. I am at risk of losing anything that wasn’t saved in the iCloud now.

not enough space for mac update

Resolution So Far (Nov 20th, 2020)

Had to take it to a Mac repair shop, Mac Phone Support could not figure it out; the Mac repair shop needs 3-5 days minimum. I am looking at buying a replacement Mac in the meantime. The new Mac M1 chip laptops seem like a good choice, and to have a backup back for future issues.

Jan 15th, 2021 – Macbook Big Sur Error Update

I had to erase my drive, reinstalled Catalina operating system, then upgrade to Big Sur. I lost my drive completely, and everything on it. Since I didn’t have Time Machine or anything that wasn’t on the desktop backed up, I lost 2GB of data from the past 2 years.

Now I have a desktop and laptop and have them synced, and I got the apple’s Time Machine backup going in case it ever happens again.



IreneDecember 7, 2020 at 5:49 amReply

Did you fix it? I am currently going through the same thing and need it for finals week.

Thomas JDecember 8, 2020 at 1:11 pmReply

I am afraid not. It tore the hard drive, I lost everything that was saved to the drive; fresh install after a week of the shop trying, like a new laptop. I lost a LOT of data.
Emma LitvinovDecember 25, 2020 at 8:51 pmReply


I had the same issue and solved it in this way:
– From internet recovery (spinning world icon) (cmd+alt+r) : go into disk utility (same screen as you’re showing above). Erase the “Update” disk container as shown in the picture above, and any other disks that are not the one your information is stored on (the ones that are not greyed out) (you can tell by seeing how much space is occupied on each disk). Also, try running first aid on all of them, you might be able to see more information. You erase and delete them by pressing the “-” in disk utility. In my case, I had 3. One was “Macintosh HD”, the other “Macintosh HD – Data”, and the third “Update”, like you. My “Macintosh HD – Data” was greyed out. So I deleted “Macintosh HD” and “Update”. The one named “Macintosh HD – Data” had the most information on it so it had to be the one I had my files in. You do not have to delete anything under “Disk images”, only under “Internal”.
– After doing this, I pressed “first aid” on the disk that was greyed out/locked. In my case, it was Macintosh HD – data, it asked me to enter in my password and this caused the disk to UNLOCK!!
– After this, I was able to reinstall Catalina on that disk (from previous picture) “Install MacOS”. And it worked!!

Now my computer is running on Catalina as before and all my files are intact. I tried to install Big Sur again after freeing up 47 GB of space and still, the same thing happened. So it might actually not be because of the space problem..

For now I’m just going to continue using Catalina since it works great and hopefully wait for the next update to be released, perhaps it will be easier to install than this one..


Thomas JDecember 27, 2020 at 2:24 pmReply

Eventually; my hard drive got lost and unrecoverable. It had to be wiped, I lost 2GB of data 🙁

Thank you for sharing this. Now I just save everything to the cloud.
Thomas JJanuary 19, 2021 at 11:25 am

I have since had to have the hard drive erased and re-installed Catalina, then upgraded to Big Sur. I lost 2GB of data, a lot of research, and files from 2 years. Now I make sure I have a Time Machine backup for my mac laptop and desktop.
ErnestFebruary 5, 2021 at 4:51 pmReply

It would be great to be able to see that Disk Utility screen, but that never comes up for me. It comes up to a language selection screen after the spinning globe completes.
Jigar KotakFebruary 6, 2021 at 1:38 amReply

You are correct it is not the issue with space, as even I got into internet recovery mode and used the terminal to find some big app and delete them from terminal but it did not work.

Now I am trying by deleting the update container and reinstalling the OS, I have my fingers crossed hope it works. Also I was a bit afraid to deleted the Macintosh HD as I wasn’t sure where exactly my data is.

But I guess will have to delete Macintosh HD as well since while writing this it installed and restarted but I see an error instead of apple logo.

One question thought where did you install macOS from ?? The recovery mode reinstall or startup option install?

As I am still getting this error logo instead of apple logo.

Apple support had no clue what is the issue. I also asked him if I should deleted the update container I see and he said you can try but I cannot guarantee anything.

Thomas JFebruary 7, 2021 at 9:53 am

I had to install from Catalina, then updated to Big Sur. I lost everything on my hard drive.
HaniehFebruary 9, 2021 at 6:09 pmReply

May I ask how did you made to ease the update? I have tried almost everything but it doesn’t allow me to erase update, no run first aid, like literally nothing works! it is like a bon stuck in my mac’s throat, my not-submitted thesis is there, and few days ago before starting the update because of low space i turned of the Icoud.. I just can’t believe what happened to me and no idea how to fix this shit … :(((
Any thoughts? I know you guys went through the same but when I saw your comment I was so happy that I may fix it! But the erase won’t accept.

Thomas JFebruary 11, 2021 at 9:20 am

You will have to reformat the hard drive 🙁 if you do not know how, you should take it in to a mac repair shop and have them do it.
RebeccaFebruary 14, 2021 at 9:48 pm

Try using target disk mode to access your files. You can save your thesis onto another computer and at least not lose that.

FarhadFebruary 11, 2021 at 12:59 amReply

Thanks a lot1! that’s worked for me 100%

MerlyFebruary 15, 2021 at 6:15 am

I am going through the same thing. I can’t believe it the update ruined my computer. I do not know what to do because I do not wanna lose my files. I would be greatly appreciate if someone can help me🙏😇

Thomas JFebruary 15, 2021 at 8:24 am

Take it to a mac repair shop like UbreakIfix
sabrizaFebruary 14, 2021 at 3:15 pmReply

How long did it take for you from internet recovery ( the spinning world icon) to disk utility?

Thomas JFebruary 15, 2021 at 8:25 am

About 15 minutes every time
SimoneFebruary 17, 2021 at 3:38 pmReply

You should be working for Apple as a tech!
They couldn’t help me for 3 days!
I tried what you said step by step and it worked! Like perfectly.
Thank you so much!

MOHAMAD SADAR UMARJanuary 19, 2021 at 4:56 amReply

Would you show with pic? I have the same problem too and have no idea to fix it 😭

MaryFebruary 2, 2021 at 9:34 pmReply

I am having the EXACT same problem. How did you finally erase the hard drive? Right now, I would be thrilled with that outcome. But I can’t even figure out a way to do that.

Thomas JFebruary 2, 2021 at 10:17 pmReply

I had to take it to a mac repair shop. UbreakIfix, I was even recommended to not do it myself and to bring it into the shop by the Mac tech over the phone, after two hours of trying to figure it out over the phone with her.
Gwilym AttwellFebruary 4, 2021 at 6:27 pmReply

Any feedback on why the system doesn’t like the password on the internet recovery screen / why using the AppleID/password won’t do the trick?

Thomas JFebruary 7, 2021 at 9:54 amReply

No I have no idea why that kept happening. Afterward I tried resetting it from cloud ID and it worked fine once I reinstalled the hard drive and re-updated it to Big Sur.
Paulina ZadloFebruary 8, 2021 at 3:01 pmReply

This is EXACTLY what happened to me. I wanted to have it serviced, but I guess there is no point so I will just erase everything. Thank you for writing this article!

Thomas JFebruary 9, 2021 at 9:59 amReply

Welcome; yes, save yourself the pain and effort. I lost 2.5 years of data in my downloads folder that wasn’t synced with cloud, but after 2 weeks of messing with it, I couldn’t wait any longer.
jFebruary 10, 2021 at 4:46 pmReply

hi can someone help me i do not have disk utility. i have startup disk showing up. my mac is a macbook air 2014 model.

Thomas JFebruary 11, 2021 at 9:23 amReply – if the screens here do not show up, then you probably are going to have to revert back to Catalina, call support and/or take it to a repair shop. My mac repair bill for them to fix it at UbreakIfix was only $48; hope that helps
JohnFebruary 12, 2021 at 3:47 pmReply

Another fairly simple way to get around this problem is to install a new System onto a USB attached SSD. You can then boot the machine from it and recover your files. And possibly use the migration Utility to get back to a working machine before recovering the mess on the Internal device.

Note that on later machines that have the T2 security chip, you’ll first need to boot to Recovery Mode and use Startup Security Utility to allow booting from external disks.

AziFebruary 14, 2021 at 10:42 amReply

I have lost 9 years of family photos and videos. Stupid Apple at least warn how many GB is required before installing a new OS update.

Thomas JFebruary 15, 2021 at 8:25 amReply

I lost 2 years of data as well 🙁
sabrizaFebruary 14, 2021 at 3:17 pmReply

How long did it take for you from internet recovery ( the spinning world icon) to disk utility?

Thomas JFebruary 17, 2021 at 8:56 amReply

About 15 minutes, every time.
MerlyFebruary 16, 2021 at 6:35 amReply

I got all my files. So happy.

PeterFebruary 16, 2021 at 6:08 pmReply

I went through a similar process. I think its important to complete the first aid process and also delete the existing volume. This can all be done through the utility desctibed above. BTW i also deleted all data but had this backed up on a different computer.

The system reinstalled Sierra. All in all very frustrating but at least I’ve got the laptop back working.

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