An error occurred preparing the software update - Big Sur

I have the exact same problem. My local apple service workers say that the only solution will be to completely reinstall Mac OS with all the data on your laptop being lost if you dont't have a backup.

Is there any update to this issue? Also happening to my Macbook Pro 2017 13"

The only answers I can see is to accept complete data loss and reinstall original OS via Recovery.

One would like to think that there is surely a more appropriate solution, especially given it went through fine on my works older MacBook Pro (2014).

Same exact issue.

After a ton of time and research; I figured out my laptop didn't have enough space (9.5gb) and big sur was 13gb; sooo; I am making a story out of it here: https://ibhuman.com/an-error-occurred-preparing-the-software-update-macbook-pro/ - normally, the update checks space first, but big sur is messing up there.

Thanks for your suggestions Fred. Seems a little extreme for me to consider at this stage though. I don't think Big Sur is for me if it's this challenging to to a simple upgrade. Catalina is motoring along just fine.

What are you seeing, when you try to install, Macintosh HD doesn't show up as an option?

How are you installing it, Software Update from System Preferences?

What Mac Model do you have.

The more information I have, the better I can assist.

Hi, I have the MacBookPro Touch Bar 13" 2017.

This happened to me also, so initially, the only option I had was to restart as a target disk or restart from the menu as it did not display any startup disk, so I went for a restart.

The install came back up and went through without any errors the 2nd time round.

I now get the Big Sur welcome screen. So far - all is well.

Hope this helps. Thanks

I have the exact same problem since yesterday. Please if someone knows a step by step guide through this mess.... I made a time machine backup of my Macbook Air 2018 128gb before i started the upgrade from Mojave to Big Sur.

can't follow Cfred2020 advice because when in macOS Recovery my mac does not recognize my password although it is the correct one.

How can i delete a file on the disk when i don't have access in the first place? My MacbookAir 2018 128gb gets stuck at 7 minutes remaining for the update and gives me too the above message as tartangear

I called Apple support and they erased my Macintosh HD drive completely, used my Time Machine Backup to get my Mac to its previous state (Mojave) and then i downloaded the Big Sur again and installed it without problems. It took me about 35 min to install it.

They told me that probably there was a problem with the first downloaded file and it caused many problems to the structure of my hard drive (at some point I head 3 Macintosh HD showing up in Disk utility). If you have a TM backup, go ahead and erase everything do everything from the start. Good luck everyone.

Hi dineshbhongiri,

The prohibitory symbol means that your Mac has an operating system but it's not a version that your Mac can boot into. Could be something got corrupted during install which happens sometimes.

The solution is to boot into Recovery Mode and reinstall MacOS.

Press and hold the power button to turn off your Mac or until the screen turns off.

Next, turn on your Mac by pressing the power button and immediately hold down the following keys command r to start up from Recovery Mode.

Once in Recovery Mode, you can use disk utility to check the drive for any errors and then proceed to Reinstall MacOS.

Hope this helps

@AshleyDee91

Great stuff! I'm trying to figure out how the installer let you upgrade or update if you did not have enough disk space? How much space did you need to clear up ? I know for a fact that installer will stop you if you do not have enough space, I think it should be 35GB or something like that. Was this the update from 11.0.1 to 11.1 ?

Hello,

I have the same problem on my MacBook Air 2017. First I thought the small free space on my 128gb drive causes this problem but even performing a clean install produces this error message. Restoring back to Catalina is no problem though.

Does someone get to a fix in the meanwhile?

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.

Hey there,

I had also this very annoying issue mentioned here.

I got almost insane cause I tried every suggestion.

At the end, one small hint in a video of mrmacintosh got my attention: https://youtu.be/bpXm_V_IJhc?t=85

The DNS settings of my router.

I am using PiHole and nextDNS. So I turned those off and used the default DNS of my internet provider. Afterwards I downloaded Big Sur again, created a USB installer, used the USB installer to erase my SSD again (just to be sure) and finally got the installing running without any issues.

Hopefully this advice will also help other people.

I would never have thought that my DNS server could be to blame.

akl_17,

Thanks for replying, I will be happy to help.

You need to back up your Mac before doing anything as erasing will cause you to loose data as it will erase the disk even if it's the disk update. Always back up before erasing or doing anything. Unmounting will not cause data loss but always best to be safe then sorry.

Hope this helps.