An error occurred preparing the software update - Big Sur

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?

after "sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume"

is there anything else need to be done?

I forced eject it and put it on the dead Macbook, see the Big Sur installer, but that really takes a long time without any progress bar or indication anything is happening.. So I wiped the USB3.0 flash and try to make the installer again. 

Will see if that would help.

Thanks for the quick reply. I wish there was a way such as a live chat where where I could help you more in real time. If you are on Twitter I believe they have a DM feature.

I had to made a usb stick today of Big Sur so will get back to you first thing tomorrow morning with the exact command I used to create my own drive successfully

Hope this helps and we’ll be in touch.

Hi Sacha

Yes it works, I eventually resolved to call apple support to finish the installation and had an amazing patient senior technician who helped through the final steps. What is the problem you are facing now ? I’ll see if I can help.

after i turn it on...

there ws a disk image written : "mac OS installer"

and connect to wifi.

after I did this the normal home page comes where I log in and after the progress bar is hal,f the apple logo on the black screen comes up with a progress bar showing the time remaining.

did it happen with you? or you were able to login from the home page? because I dont know how to backup laptop in this condition? Please help

Hi AshleyDii..

Could you please help me wth this?

after i turn it on...

there ws a disk image written : "mac OS installer"

and connect to wifi.

after I did this the normal home page comes where I log in and after the progress bar is hal,f the apple logo on the black screen comes up with a progress bar showing the time remaining.

did it happen with you? or you were able to login from the home page? because I dont know how to backup laptop in this condition? Please help

Hi Soren Pearson, I am facing the same issue with Macbook Air 2017 and have tried restarting it again and entering the password for the startup disc which does not accept the correct password. I haven't backed up my data on the time machine and do not remember any encryption password for FileVault. Please help...

Hi Fred, do you manage to install using a USB stick?

With USB stick and I select the Big Sur installer, it still lead me to the MacOS recovery mode, and as always my password would not work so it becomes a dead loop.

Hi Soren,

Hoping you can help! I’ve experienced the same issue as everyone else (no time machine backup, unable to proceed any further with the big sur update).

I have created a bootable installer of Catalina, I go to install it by holding option when turning the computer on and I am unable to select the Catalina USB bootable drive as it says that the drive is “locked”. I followed the apple instructions correctly and the USB is formatted correctly for Mac.

Not sure where to proceed from here! As mentioned, I don’t have a backup and can’t risk losing my data.

Can anyone explain the process of using another Mac to be a target device?

Thank you!

Hey, I had exact same problem when i was trying to update the mac os to Big sur. I tried your suggestion and press Option and then turn on the computer. i end up having a sign of circle with a line in it.

any more suggestions?

Thanks

I am encountering this error on an Intel-based Mac. Insufficient disk space without warning. The last OS was Catalina.

Upon error, it asked to choose a startup disk, in which only the Bootcamp drive was the only option. There is no option to return to the regular login or my original macOS drive.

I have entered the recovery mode through [Option-R], the menu reinstall macOS only gave the choice of Big Sur version. Surely if I proceed with this, I will still get the same error since the disk space is not enough. Disk utility can still detect and mount the drive of my macOS.

I have then tried the recovery mode to reinstall the macOS that came with the Mac through [ Shift-Option-Command-R ], this brings me to Maverick OS installation. However, it cannot detect a disk to install at all. Disk utility is not able to mount those partitions as well.

At this stage, how can I go back to Catalina or install Catalina? Will the bootable installer solve this? Which partition has my actual data, the one with ending "Data" or the one without?

I have not erased my drive so hope the files are safe. I do have back up but it is not up-to-date. Thanks!

I'm glad you did not erase, because I have a workable solution for you!

https://mrmacintosh.com/big-sur-upgrade-not-enough-hd-space-serious-issue-possible-data-loss/

I feel bad for others that have been caught up in this issue for the past 3 months. So many bad experiences leading to complete data loss. It took quite some time to piece together what was going on here, even more to work out a fix for the problem!

HI Brian

i have exactly same problem.

can you tell me how to create MacOS Mojave usbkey installer as you said,

then how to you install to an external drive?

Do i need to format the USB Mac OS Extended ?

Thank you

Hi,

This is very helpful, but when i hold down the option /alt key and power back on my mac, it only comes up with the macOs Installer to click, and then when I choose this, it takes me to my login page as normal, but once i’ve logged back in (this is the only time my password is accepted anymore- it is not accepted in the recovery mac) it continues with the update.

Any help would be greatly appreciated- I’m going round in circles here, and i’m clearly not the only one with this problem!