MacOS Big Sur get stuck on 12.18 GB of 12.18GB

Did you try connected to a different network or using a vpn?

I have no idea how Apple has cocked this one up so bad, but the one and only thing that worked for me was a network change. Never had any trouble with this before, and don’t have any weird router settings or anything.

connecting to a vpn was a lot easier than trying to putz around figuring out which setting in my Google Wifi system Apple didn’t like.

I finally got around the install issues by creating a second admin user (and down grading the original admin) then doing the download and install overnight. Seems that all the issues I had with the Catalina upgrade (iMac 21.5 late 2015 fixed 8gb RAM) went away when I upgraded to Big Sur. Now the issue is that I can't get rid of the original user. System Preferences hangs up when I try to delete the user. Just a pain the butt when I login accidentally with the original user as my iMac hangs up trying to optimize.

I ran into the same thing except mine stuck at 12.20 when trying to update from Mojave to Big Sur. Tried all sorts of methods, to no avail. Finally relented and used “clean my Mac x” to clean up the Mac, which I feared may have a virus on it. The cleaning seemed to work. Re-attempted the update, which got hung up at 12.20 for about 2 minutes, then finally busted through and got to the installation window. May have been a glitch on Apple’s part, but at least I now know there is no malware on my Mac. Also, the update must be large, as it takes quite a while to install, esp over WiFi.

I tried many many techniques found here and on macrumors forums. The thing that finally worked was connecting to a vpn prior to starting the installation.

Well done my friend. I just had the same problem upgrading from Catalina to Big Sir, and it stopped at 12.12GB. I set my internet connection to inactive, then back to active and I was able to resume my download. :)

Just wait it out. It takes a while.

It is mind-boggling to me the fact that Apple is not jumping in to help with this issue. My Big Sur install started last night around 8:00 PM and by 2:00 AM the progress bar was almost to 100% but it didn't move after that. Looked again this morning at 9:00 AM and it was still at the same place. Some people online recommended to click on the power button and it would "wake up" the install. I tried that and it didn't work.

Now I have restarted the computer and it got worse, it only shows a black screen sometimes and some other times it shows password recovery screen.

I now have restarted the computer pressing down command and R before the chime to enter recovery mode and run disk utility's first aid and then Reinstall Big Sur utility. Right now it looks like it is either downloading or running the install with 18 minutes remaining. I also connected the computer via ethernet cable in addition to WiFi just in case the issue was a faulty (unlikely) wireless connection.

I don't know if this is going to work but at least I don't see a black screen... I'll keep you posted if it works.

Hi. An IT professional here. On day 4 of working on 9 different machines in 3 different locations. All stuck on 12.18 GB. MacBooks, MacBook Pros, Mac Mini's, iMacs, ranging in age from 2013-2019. All stuck. I have had a couple load successfully, but none on the first day. Hoping we will be able to install soon.

After many many weeks I used the above steps with no hope at all. Surprisingly it finished download and is installing as I'm writing. I think the trick here is to randomly interrupt the progress by disconnecting internet.

I have the exact same problem. It (Finally) gets to 12.18 Gb but then stops. It then waits there for 15 mins at least before giving me the error message saying that it can't install. I don't know how a HUGE tech company can fail this badly.

I've tried doing this a couple of times since it was sent out yesterday at 6pm (GMT) and this is the furthest that the install has gone, the other times it has failed before even starting to download or it would download about 5Gb and then fail. Either way, this is not what we are used to seeing from Apple.

One question I have:

Why does their support page say that the issue has been resolved when it clearly hasn't???

Anyway, good luck with getting this thing to install mate. It seems like were just gonna have to wait a few days for things to be ironed out XD

Trying hamiltonfrommaputo's solution. Download did not start from the very beginning just close enough to the beginning to draw this maddening process out again. Hopefully the 4th time is the charm. I will update this post as things progress.

So it's two days, later - Nov 15 and I'm getting the same issue maybe ten times. Your solution doesn't start things mid stream for me, it starts over, but much faster, almost like it has some of the download buffered. But yet, after about three minutes, we're stuck again at 12.18. Pretty sure when I die, St. Peter will say good news - you've been granted access to heaven, just as soon as the final bits of your download are complete.