An error occurred preparing the software update - Big Sur

Hey Soren, I want to close the loop on our journey . . . I broke down and took my MBP to an Apple Store today. They were able to successfully do the install of Big Sur from their on-site server. However, the also noticed a kernel problem during start up - a single screen that said essentially that the "computer has encountered a problem during start up. wait a few seconds or hit any key to resume". But everything else seemed to be functioning. This led them to do a full diagnostic on the MBP where they determined that the hardwired memory was degrading. They believe this "likely" was the cause of the erratic behavior that we were seeing during the macOS downloads, the the OS installs, the recovery modes and even safe mode. It's possibly why we could not get reproducible results.

So bottom line is that you and I were following all the normal steps but the hardware likely was the problem. Probably a rare event since most memory failures occur slowly over time, not during single events like OS installs. . . . . so I'll go to my local go-to Mac guy for the repair, which should get me back into the normal Apple universe. So in a sick, twisted way, the past 5 days of macOS installation **** has been good because it means we caught an annoying problem now before it became a major problem later (which always occurs at a critical time according to Murphy's Laws).  . . . . thx againd for your help and suggestions . . . rgds . . Tracy

Hi LizethBo,

Ok, if you have another Mac you might need to create a bootable USB of MacOS Big Sur or even Catalina. Here is a direct link to the installer for Big Sur if you need it. Just run the pkg file and it will create an installer in your applications folder on the second mac which you can use to boot off the USB on the said Mac with issues.

If you hold down command r at boot, are you able to boot into recovery mode? If so can you go to Disk Utility and post a screenshot of the window for me?

Please report back with your findings and I will be able to help you further.

Hope this helps.

tartangear wrote:

I tried to do the Big Sur update and near the end of the installation i get the message

"An error occurred preparing the software update "

and then i'm asked to select a startup disk.

I've tried rebooted a few times and it always happens.

I assume i'll need to do a recovery of some sort.

I tried to reboot with CMD+r and then i was asked to enter the user password, which wasn't accepted (even through it's definitely the correct password).

Can anyone suggest what i should do next?

https://discussions.apple.com/content/attachment/5304c99c-3ed2-408b-b6a4-222640aef9c1

https://discussions.apple.com/content/attachment/61e88eb9-6f02-4267-8c93-c209a5f3045d

You do not say what exact Mac this is?

What macOS are you currently running before the upgrade/update?

I suspect this is a server issue being overload— slow downloads can cause corruption in the installer.

If you have the full installer, you can see it in your Applications folder "Install macOS Big Sur.app"

If it is there— reboot into Safeboot mode an click open the installer in your Applications and see if it goes without issue.

If no resolve delete thjat installer/empty the trash and try anew.

You can always Call Customer Support (800) MY–APPLE (800–692–7753)

Dongsun

You will need to use another mac to make the usb installer

Here is the apple link to making a usb installer

https://support.apple.com/en-us/HT201372

here is the program i use but it only works well if you are still running mojave

https://diskmakerx.com/

Here is a good article for installing to the external drive

https://www.macworld.co.uk/how-to/macos-external-drive-3659666/

Be sure to use an external drive that is large enough to backup your data to

Brian

Hi Tracybjazz,

How did you first obtain the installer for Big Sur, from Software Update?

Are you currently using Mojave or Catalina? When updating to Catalina a data disk is created. You can read more about it here: About the read-only system volume in macOS Catalina.

I would delete the application "Install MacOS Big Sur" from your applications folder and redownload it from the App store again and then use the USB stick and try it from that.

I've had situations where the software update installer didn't work or show up but when using the direct link it would show up fine and download. If the direct link doesn't work from your Mac again then try the USB stick.

How to create a USB installer for MacOS

Dowonload MacOS Big Sur - App store link.

Somehow it's not letting you do it from the computer itself.

I assume you are fully up to date via Software Update?

Hope this helps.

I creates an external boot disk with Big Sur, erase my MacBook Pro, reformatted the drive, and completely clean installed Big Sur then restored by data from a Time Machine backup.

Finally a success message! The installation finally worked.

I tried installing via usb stick as well as re-downloading the installer several times. Finally I restored my existing Catalina system and then created a new container in the APFS volume for the installation. I downloaded the installer again under Catalina and then started it under Catalina and installed it on the other volume.

Hi Sabueno,

If you have access to another Mac, I would download the installer for Big Sur, run the .pkg file and Install MacOS Big Sur will appear in your Applications folder. Then create a bootable installer and try booting the said Mac off the USB installer and try the install that way.

Hope this helps.

In the case of my mac i had no space to inicialize so the support told me i need another mac to pass my data onto (do the target disk mode), then erase it all and download the macOS

but maybe for others this might work:

1. press the on/buttom and release
2. than hold option command R until a « world » appears

other option the suport showed was:

1. press the on/off buttom and release
2. than hold option command P R until the computer makes 3 times the sound
3. release the 4 buttons
4. it should appear 4 options, select the one that says install mac Big Sur
5. if you have enough memory it might work

Hi shaobo626,

The prohibitory symbol means that your Mac contains an operating system but it's not able to boot to it.

Are you able to boot into recovery mode? After you hear the startup chime, hold down command r to boot into recovery mode. Once in Recovery mode select reinstall MacOS and you should be good to go. This will not touch your data but reinstall the operating system and address the issue.

If you are not able to boot into recovery mode, you might need to use another Mac to create a USB stick with a bootable copy of Big Sur to reinstall the operating system on the said Mac.

Hope this helps.

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.

Hi Tracy,

Thanks for the two updates. I feel that’s progress that it got further along in the install.

So strange that it would stop like that even from the USB install and you having plenty of disk space.

One thing you could try doing is Safe Boot. Hold down the shift key when you boot your Mac and release it when yous see the login window and Safe boot in the menu bar. Try the install that way from your applications folder.

Yes good idea about having additional backups. You could even consider a clone via carbon copy cloner.

Hope this helps.

jecoycoy,

See if you can boot into safe mode by holding down the shift key when you start your Mac.

If you hold down down command r when you start your Mac, are you able to boot into recovery mode?

Hope this helps.

I couldn't get into the issue Mac.

Double click the Macintosh Data and the same issue remains.

"Start your working mac in a normal manner --> login --> you will be prompted to type the password for the hard drive of the mac that's having trouble. They accepted my password finally (and any prompts from here onwards accepts my correct password)! Now delete some stuff in the hard drive of the mac that's working! I deleted some applications that are easily downloadable from the internet/are free until my drive had about 58GB of free space (no specific reason why I freed 58GB - I just wanted to play it safe). Eject the hard drive."

Can you mount the old Mac in Disk Utility?

"Start the other mac (i.e. working mac) in recovery mode --> go into disk utility --> attempt to unencrpyt the hard drive of the mac that's having trouble (I can't remember if my password was accepted then but I don't think so)"

Okay

I would try this if you have an external HDD or SSD and a spare usb flash drive

Create a mojave installer this may help big sur - How can I make a bootable USB copy of Mojave downloaded from Apple when the file is an app and not a disk image? - Ask Different (stackexchange.com)

Then install Mojave to the External Drive this may help How To Install macOS On An External Drive - Macworld UK

Boot from the Mojave external drive

Hopefully it will unlock your data drive now

Then you can backup some data and clear some space.

That is what Is basically what I did and I was able to clear the space

And after the reboot it was able to finish the big sur upgrade.

I hope this helps.

Brian