Big Sur installation stuck at "Less than a minute remaining..."

I too have had the "Less than a minute remaining" message. And every time I rebooted, the progress bar moved slowly along and ended up with "Less than a minute remaining" followed eventually by an error message. My immediate thought was to panic. There seemed no way of abandoning the update and returning to the Mojave operating system. I had a look at my backups, my precious Time Machine backups. I restarted in Recovery Mode. I saw that disappointingly my last backup was a year ago. Some would say that you should do a backup immediately before upgrading to Big Sur. But is there any point? I tried restoring from the most recent Time Machine backup and got an error message - it woudn't let me! Maybe because the operating system was incomplete. I notice someone else here also couldn't restore from Time Machine and got an error.

My solution won't suit everyone. Just when I was resigned to buying a new Macbook and using it to access the documents and data on the old one, I discovered that I had already made a bootable clone USB drive and when I pressed the Options key while rebooting, it allowed me to boot, rather slowly, from that USB drive. I then saw that although I had started with about 24gb of free space on the hard drive, it was now about 840 mb. So the reason for the problem, as others have pointed out, is that the upgrade process requires a huge amount of HD space (does anyone have an accurate figure?) and when it runs out of that space, it hangs on "less than a minute remaining". The remedy was therefore simple - delete more files from Documents and from Downloads and anywhere else where you can find large files. Copy them to a USB stick or USB drive, to be copied back later or copied onto a different computer. Then reboot, and in my case the upgrade to Big Sur completed very quickly and the temporary files had already been deleted leaving me with plenty of disk space.

So I suppose the question for the experts here is: if you don't have a bootable clone disk with which to start your Mac, how do you create one without having to do it with a different Mac? Or is there a different way of booting up so that you can delete some files and make more space?

I had this same problem on my MacBook Air where my computer was stuck in the “less than one minute left” black hole. Recovery mode was no help as it was not recognizing my password. I took it to the Apple store and they had to wipe it completely. I’d recommend staying away from Big Sur until they figure this out as at least in my case they had no idea how to fix it.

Apple - this is appalling. I moved to Apple because Windows updates were a disaster. My MacBook has been dead for 5 days now. Apple support told me to create space by moving stuff to my other Mac. Fine - spent £40 on a Thunderbolt cable. Cleared a load of space. Still have the same issue.

Surely it is coding basics to ACCURATELY CHECK there is enough disk space before updating an OS. My seven year old could tell you that.

Next step shift the rest of my stuff. Wipe the hard drive and have another go.

Apple has become a bunch of hopeless amateurs.

I have encountered the same problem. First phone conversation with Apple said to let the installation process proceed on its own. Tried that and got an error message. Second phone conversation was 2 hours long with a tech. She told me that the disk to put the OS on is not there anymore and there must be a glitch in the matrix which has caused this. I am waiting for a phone call back as she consults her techno wizard friends. I’ll update this later.

Oh no! This is exactly what’s happening to me atm — I took my mb air to an authorised tech shop yesterday and have been waiting to hear back. Things are slower here in Portugal. I’m praying they don’t have to wipe it.

We had a similar problems in old MacBook Pro's, got stuck there at 1 minute remaining for few hours, few devices we left it overnight and it got completed, couple of them we tried hard rebooting and it helped, if you are even struck after that, better to take it to nearby Authorized Apple Centre, we being a mobile app development company can't afford such delays during our productive hours, apple has to resolve these glitches, common this is 2021, but still there are these lame issues.

Sciflare Technologies Pvt Ltd

Chennai

Update: I’m having to erase my laptop and start from scratch. Luckily there is nothing of importance that will be lost. Tech said since there are enough people experiencing the same problem that the engineers are looking into it more deeper. Still doesn’t help my problem right now

Thank you for your detailed response. Yesterday I spent 10 hours to be able to fix this issue.. During that time, I even learned the basic commands of Terminal!

Without seeing your comments I also discovered the same procedure would help me. So I first learned how to open the recovery mode, then there I found out how to use Terminal. Then I checked for codes to see the disk space etc.(a lot of research...) As in your case, my Macintosh hard drive was also full. So I connected an empty 500 gb external hard drive. By using coding I tried to copy files but it didn't work. By accident, I discovered Terminal> Shell > Open Window. Then I could see all my files/ folders in my Macintosh HD, however I couldn't move them. Then I decided to install Mac Big Sur on my 500 gb external HD. But first I had to learn how to format it the proper way (omg so much thing I had to learn in one day!!) Through one page, I found that it has to be APFS (Apple File System) but there was no such thing in the options.. Then through another page, I learned that I have to choose GUID partition from the drop down menu. After doing that, I could choose APFS.

Anyways, after erasing my external hardrive (so formatting it as APFS), I also installed Mac on that External Harddrive and could open up my laptop again. However, I didn't see my old files (as it became basically a new computer on external HD). So, to be able to see my files on Macintosh HD, I again opened the Terminal and then looked up for codes to be able to see files. After finding the files, I could free up a lot of spaces (using delete code for the folders I want to remove). Then, I closed the computer, remove the external hard drive, and tried to open it (by thinking that it will now complete the install as there is now a lot of free space). However, it didn't complete. It was in a loop so many times. That's why I again opened recovery mood and this time chose Internet Recovery (one youtube video was describing that this option keeps your files, however there might be a risk.). Anyway, when I chose internet recovery, the computer asked me where to install Big Sur (there was only one option (Macintosh HD) as I removed external HD and it showed that now I have 75 GB free space which is more than enough. After an hour or so, It installed Big Sur on my computer. However, I lost all my data :((( luckily I don't remember having very important files. Eventually, this was not a good experience for me even though it is not the end of the world. I really wanted to rest this weekend and I spend my whole Saturday with this **** :(

I don't know what that "looking glass" option you are referring to. Maybe if I knew it, I could also copy my files (because I could see them through the terminal, but couldn't copy them by coding. They were not visible in the Finder.)

Anyways, from this experience, I can totally say that Macbook and update procedures are not good. My completely fine working computer got into this mess for nothing.. They have to inform users that at least 35 GB space is needed, not 12 GB!! I lost all my data.. Such thing I never had in my Windows computers (the current one is 8 years old, working perfectly..) Please Apple pull yourself together!!!

I did the same but once I tried to download Big Sur onto my external hardrive it only downloaded until it said "12 minutes remaining" then it just restart the computer.

I figured I didn't disable the security in recovery mode so I did that, tried again and same thing happened only it kept restarting over and over until I held down command R.

Any idea how why its not finishing the download? I really don't want to accidentally crash my computer :(

I have previously described booting up from a USB drive which has been configured as a Mac startup disk, so that I could delete some of my files on my Mac and enable the installation of Big Sur to be completed. It seems to me that another way of doing it, if you have another Mac (or can use a friend's Mac), is to connect it to your Mac with a Firewire or Thunderbolt cable. Then reboot the non-bootable Mac holding down the 't' key, which puts it in Target Disk Mode. If this works, the Mac hard drive will appear as a mounted drive on the other Mac. You can then go into the problematic Mac and delete some files. Do remember to empty the bin after deleting items, otherwise you won't be making more space.

I find it rather shocking that any Mac repair man would opt to solve the problem by deleting all your files and giving you a factory configuration of Big Sur. At the very least a competent technician should be able to access your hard disk and copy your work to an external drive. As mentioned in my earlier post, Time Machine Restore does not seem to work when your Big Sur installation is incomplete, but others might have different experiences.

I cannot believe this problem had been going on since November and Apple hasn’t fixed it. I just did the upgrade to Big Spur and am now stuck in this loop. WTH! So incredibly frustrating. If I didn’t have enough space on my HD why on earth did it allow me to even begin the update.

I got a snarky “support” person via chat today who basically shamed me for not ensuring I double backed up everything before I did this update. um, hey Apple, maybe don’t make a computer update that has the major potential to put people’s computers out of commission and potentially wipe them clean?! they are seriously 0 help with this. infuriating.

I had the same issue with my MacBook Air and was stuck in an endless cycle. I wanted to try the suggestion to download Big Sur to an external drive, and open up space on my laptop, but I lost the cords for my drive, and with a current lockdown couldn’t replace them quickly. I had never backed up to an external drive, since this is a secondary computer. After much distress, I decided to look on iCloud. All my documents were saved. So, I erased the hard drive and re-installed Sierra. I was able to recover all my files from iCloud.

Had this happen when a user didn't have enough drive space available. I ended up shutting down, booting into Internet Recovery Mode(Shift+OPT+CMD+R), going into Terminal and deleting the /Volumes/Hard Drive/Applications/Install Big Sur.app file from the data drive. Once I did this and rebooted it finished the install. Apparently this is a known issue with Big Sur allowing the install on drives that do not actually have enough space.

If you go back to the main recovery start up screen click the download Big Sur option and then select your external hard drive as the destination. It takes about 40 minutes to download it to the hard drive and then it will automatically restart the computer and begin the install I think I started mine at like 3 AM and went to bed then at 8:30am I skeptically clicked to wake up the Mac expecting to see the recovery screen again and but saw the set up screen instead! So I’m not sure exactly how long it took but under 5.5 hours.

Doing the set up is a little confusing because I think you’re kind of setting up the hard drive as a computer essentially. I was able to delete a folder I know I had a back up of that was about 96 gigs to free up space and that was located in HD data and I think Volumes. It was tough like the OP said to navigate around but I searched a file name and once I saw that file name at the very bottom of the finder screen I could click on the folder and bring up files that way.

good luck!