an error occurred applying the software update

mreed gave a link which shows all the startup to recovery command types.

And, if you get to the select the language screen the first thing I woudl do after getting to the install is to access the utilities and run Disk First Aid on your drive.

First, seeing your hard drive listed should give some peace of mind. Then you can fix any corruption that might have been caused by the failed install attempt.

Update: I had to scrounge around the 'net and collated useful tips found non-apple forums.

1/ Big Sur (also known as Big Sour) is full of security and privacy kinks that trips up so many apps (including Apple apps like Numbers) and devices (eg printers).

2/ Once Big Sour is embedded as the OS for your Mac device, it can't be reset to an older OS.

3/ Embedded, Big Sour does need to be recongifured. You must save all important apps (including Apple Apps like Pages, etc.) and files to a non-apple cloud account or USB drive because in Apple Store many older Apple Apps and older apps are not available for Big Sour.

4/ Reconfiguring does erase all data like factory reset. So I repeat save every important app and file because in Apple Store many older Apple Apps and older apps are not available for Big Sour.

5/ After saving the important apps and files; Click on the apple icon select Shutdown (or restart if you have quick reflexes).

6/ Start the machine at the the first appearance of the apple icon simultaneously press Command and R for 5 to 20 seconds (this varies between machines). This step is so temperamental that you may need to do a few times.

7/ When the utility box appears, you will start the dreaded process of deleting drives and doing first aid. The aim is to delete various drives and folders that may contain apps and files that were kinked by Big Sour. The kinked apps and files are corrupted and will affect running them hence crashes, app functions don't work, etc.

8/ By doing the factory reset and resinstalling Big Sour, the OS will function.

9/ Use the Apple Store to download Big Sour compatible apps.

10/ Now start reinstalling the apps and files you saved in step 3 and 4. DO NOT EXPECT ANY LOGIC TO WHERE APPLE LIST APP/FUNCTION SWITCHES. After installing them, the swearing will intensify as each app/file may have security kink that will involve going into various MAC system menus to locate the glitch switch for example Numbers apps scrolling is not logically in the Numbers app so it was #$%$%#$%#$% to find that glitch switch is in the System Preference >Touchpad. APPLE forums were difficult finding easy tips on were the swithes are. Research non-Apple forums and you will find straight forward and easy tips on where to look to the glitch switch.

11/ Printer connections are most affected as Big Sour security kinks will cause problems. Printers needs to wireless. If your printers have sleep mode and deep sleep modes, switch those modes off, or else when in those mode Big Sour security kinks will kill off the printers connections not recognise their drivers/firmwares and you will have reinstall their drivers.

12/ Some reinstalled apps and files will have minor glitches that you can find workarounds.

13/ After 3weeks of trying to find fixes for glitches, I can use some of the important apps and files. Other apps and files can only be accessed and edited through online web-accounts and Google docs (Big Sour refuse to run them). Every couple of days Big Sour printers connections are $%$^$#. Sometimes while making an urgent online bank payment and needed to print a receipt/invoice/order or to print and urgent document that needing signing that I find out the Big Sour has cut the printer connections that I have to screenshot the receipt/invoice/order, send to other apple/PC devices to print off.

Hello. I got the same error. I tried over and over. Same error kept coming up. I was panicking. Finally, I held down Command + R while rebooting and got a menu. I first had to connect to my wireless network. Then I choose the install Big Sur from the internet option. I chose continue and after about 40 minutes it rebooted perfectly and I am back up and running. Basically I downloading Big Sur from the Internet and installed it that way. So far, so good. Good luck. Hope that helps.

If you use Recovery Mode (Command-R) you won't lose any data. You're overwriting the OS but that being said, you should always have a fresh backup when upgrading just in case. It's not a matter of IF you need it but WHEN you need it.

I took it to a retailer like it suggested in support. The wanted $95. I left. Prayed. Went to church and the genius there fixed it for free. Reboot worked. Reinstall worked. Lost all data. No external drive to back things up on. No major. All is the the clouds.

I have done CMD+R when it gets to the bit where I have to login it says my password is incorrect, I know for a fact that it’s not wrong, just to double check I reset and then logged in with the same password and it worked. No when resetting holding CMD+R the password does not work when picking my profile :(

This seems to be working for me, it looks like my MAC dropped my Wi-Fi connection during the update to Big Sur and I got the error popup. I followed your instructions and was able to reconnect my wifi (had to plug in a keyboard and mouse as obviously Bluetooth wasn’t available) I’ve restarted the update. So far seems to be updating. Thank you for your input.

Are you able to get to the utility menu? Do you have an Apple store near you? If you have everything backed up to the cloud, they will install a new OS for you for free. They did mine for free and reinstalled the OS in about 30 minutes. I brought the computer with me and they cared for it well. I was super surprised how nice and easy it was.

Did you try what was suggested above?

“restart your mac on the screen where is says an error occurred while applying the update and as your computer starts hold down command and "r". “

It worked fir me. Good luck!

Its February 2021 and I have waited to do this update in order to do not come

to such an early release problem, but still, here I am.

I have exactly the same screen, but even stranger when I start in recovery mode

it asks which account I want to login and I select the only one there is and asks

for my password, which I am 100% sure it is correct but still it does not accept it.

There is also the option to unlock the Macintosh HD using a password which also

seems not to be the pass I am using for 7 even years on this computer.

What should I try next???? =(

Hello nisha291. Sorry to hear about your problem. Not fun. I can only suggest taking your computer into an Apple store and see if they can help. Usually software issues are fixed free of charge. Clearly they are many people,e having issues and they are not all being addressed. I think they would be able to get around the password as well. They will set it up as a new computer. That is what they did for me. Took under 45 minutes. Best of luck. I hope you find a solution. Be well.

Hey!! I just has this issue too :(

Also a student and was mildly terrifying as I was stuck out of my laptop.

However, I did regain access

First of all I used the command R hold down upon booting up to access recovery mode I then used disk utility and did 'first aid' on my disks in case this was the issue (unsure if this was useful but might as well say). At this point I was still stuck

If I clicked startup disk it would load and load and give me no options

I then rebooted and held down alt or option key depending what laptop you have. And this boots you to a screen where you decide which disk you use to boot your laptop.

Previously it has been trying to boot using mac installer. Instead select your mac HD drive/the other option for booting.

For me this loaded me into my normal laptop interface with ALL my files.

I deleted the big sur installer as this was using up 12gb.

Currently I am backing up 40gb of my data, and will clear up some space once this is done to try again with the update

I hope this helps someone :)

Hi! I am also a student and have been freaking out because I left my computer to update and now the same thing happened to me. I did everything you did but I’m having a bit of trouble when you said hold down the option key it didn’t pop up with anything. Please help !! :((

I had to take it to Apple. They wanted 99 to erase and bring restore. I had no back up.

I took it to my church and the geniuses there and they erased it and restored it for free. I got advice on how to back up in the future. Free.

I think this is why some updates don’t do a thing to bring positive change. Sorry if not more helpful but it is honest. Apple doesn’t love you after your purchases are made.

Hi. Sorry if this to late but I’m desperate lol. I’m at the macOS Big Sur but I don’t have enough free space to upgrade 😭. I just want to get my computer back to normal I don’t care about the update. Does anyone know a solution?