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

I was having this same problem and I want to share what helped me because I haven’t seen this fix proposed anywhere else. None of the options like turning on/off, using internet Recovery, or MacOS Recovery were working. I turned it on and off again several times and it kept getting stuck on less than a minute remaining. When I finally decided to let it set on that screen and leave it overnight, when I came back in the morning it had an error saying “an error occurred preparing the software update.” Using First Aid from Disk Utility on Recovery also did not fix it.

When I tried to use the option “Reinstall Big Sur” from Recovery it would tell me there was not enough room on the disc to do it. So I was effectively stuck on the install screen.

I called Apple and they were helpful. I was working with them on the phone on a different WiFi than I usually use as I was not at home when I tried calling them. Just to give an idea of what we tried, when I would use Recovery (turn off, turn on, hold command +R or hold command + R + P) and go to “reinstall Big Sur” from there it wouldn’t connect to WiFi and gave me an error that “Keychain ‘System’ cannot be found to store [my wifi username].” We hit cancel to get out of that (don’t choose “reset to defaults” if you get this error or else your keychain passwords on the computer will be deleted; if you save them in iCloud it may not matter if you do).

What ended up working was turning the machine off, then holding Option while it was off, and it came on with a screen to select my Macintosh disc and connect to WiFi. It let me connect to WiFi there. This took me to my desktop login screen and I was able to log in and get back to my regular desktop! Thank goodness.

From there we investigated and turns out I did not have enough space left on my disc to do the Big Sur install— the agent told me it takes 35 gigabytes, and I only had about 33 gig available (checked by going to Apple in top left corner > about this Mac > storage). Luckily I had an old iPhone backup I could delete to free up a lot of space.

The Apple agent told me not to turn my laptop off/restart it, or it would probably put be back onto the install screen. If I have to in the meantime, she said to follow the steps I described as working above to get back to the desktop.

She put notes on my case and I am supposed to call them back once I’m back on my regular home WiFi and we can restart and they will guide me through the reinstall through Recovery. I will update once we’ve attempted that. But for now, luckily my computer is actually working and not stuck on the install screen! I hope this helps someone else who is still having issues where the other proposed solutions aren’t working.

I got the exact same problem, but thanks for this forum, I could get my mac updated to BigSur very quickly and without external drives. It's indeed a not available HD space problem. I had around 42Gb on my machine, but after downloading Big Sur (around 12Gb) it got to 30Gb only and, according to people over here, it needs ~35Gb.

In a few words, I restarted the computer on Safe Mode (Cmd + R pressed while turning on), accessed the Terminal, navigated to my disk, and deleted a bunch of unneeded files. Then, I've restarted again and left the BigSur installation to get finished without any other problem.

More details below:

• If you are stuck on this "Less than a minute remaining" screen, basically you will need to erase some big files from your computer. To start the process, just press and hold the power button for some seconds. The computer will shut down.

• Then, restart it, pressing and holding the Command + R keys while it restarts. Wait while a different screen shows up with these four options below.

There is also a top menu containing Recovery; File; Edit; Utilities; Window and Wi-Fi connection on the right side. My MacBook was not connected to the internet and I decided to connect it. IDK if this step is needed, but it won't hurt.

• Then, on the Utilities top menu, I found a link to open the Terminal

• With Terminal open:

1. Type cd /Volumes and press Return to navigate to the volumes.
2. Then type ls -l and press Return to see the Volumes you have. Big Sur installation creates some volumes and you need to change the Volume you are to your Mac HD.
3. To change to the correct volume, type cd "Macintosh HD - Data" or something similar and press Return. You need to confirm what is your data volume name and replace Macintosh HD - Data with the correct name. In case you have two similar options you can navigate to one of them and confirm if it's right on step 4 below. If it's not you can just restart on step 1 (cd /Volumes) or type cd .. to get back to the previous directory. Always execute ls or ls -l to list the content inside the current folder, that way you can confirm you are in the right folder before moving forward.
4. Execute ls -l to list the volume content. In the list, it must have a Users folder (and other folders like Applications, Library, System...). We are interested in the Users folder. So, navigate to it typing cd Users and pressing Return. If there isn't a Users folder, you are in the wrong directory. Restart from step 1.
5. Execute ls again. You will see one folder for each user on your mac + Guest and Shared folders. Now it's up to you to determine which user has erasable files. It's easier if you are the only user. Then navigate to this user folder using cd username. In my case, it was cd leomuniz
6. Execute ls again. You must see folders like Applications, Downloads, Documents, Movies, Music, Desktop, etc. These folders contain the files you will need to delete. If there is more than one user, you may repeat this process for other users too.
7. To find big files you must execute find . -size +100M
8. It will provide a list with all files bigger than 100Mb and, luckily, you will recognize some of them.
9. Again it's up to you to determine what can be erased and what can't. I could erase almost everything because I created a backup before starting. Even so, there were things that I don't know what was and I leave them there.
10. Once you determine the files to erase, run rm filename for each one. You can select the whole line containing the file name with your mouse, copy it, type rm and then paste it. Example: rm ./Library/Application Support/Spotify/PersistentCache/Update/spotify-autoupdate-1.1.52.687.gf5565fe5-30.tbz
11. I didn't erase this Spotify file above. I've basically removed some big videos (.mov, .mp4) from Zoom recordings, big audio files (.wav), and some folders from old stuff. In case you need to erase an entire folder, use rm -rf foldername
12. Keep erasing files until you think you are done. It's impossible to say how many files you should erase because every case is different. The most important thing is: you need to have ~35Gb free before starting the Big Sur install. I had ~30Gb before the install. When I got to the Safe Mode I had only 19Mb remaining. And I freed around 5Gb to compensate, but I didn't calculate. I just erased all the big files I found that I know I could safely erase and this was enough for me.
13. Once you are done erasing, just restart your computer. So, close the terminal. Then there is no need to click on the Reinstall macOS Big Sur button because there is already an update process running. There is a restart command on the top menu. If you have freed enough space, your install won't be stuck on "Less than a minute remaining". It worked for me.

To index in Portuguese as well:

Atualização Big Sur menos de um minuto restante travado pra sempre erro o que fazer

After 24 hours of being stuck in the loop this solution worked for me, I now have Big Sur successfully running on my (wife's) Macbook Air (MacBook Air 2015, 128 GB HD). The issue was that there was not enough free space on the hard-drive, but because I was stuck in the loop I was not able to free up any space. I used an external hard-drive to install Big Sur on, was able to break the loop and get back into the Macbook to clear up enough space (35 GB was enough for me). After that I was able to re-install Big Sur on the Macbooks internal hard drive, without losing any files. This is what worked for me:

• Turned off the Macbook - hold down power button until it powers down.
• I used Recovery (hold down cmd + R while booting up Mac). When I got to the Recovery screen, connected my external HD (1 TB Seagate).
• In the Recovery menu, used Disk Utility to format my external HD to make it compatible for use with Mac (just google, easy to find and do)
• I installed Big Sur onto the external hard-drive
• I followed all the steps (like setting up an entirely new computer) until you are finally able to work with the new OS (please note the Macbook was significantly slower than usual because it is running off an external drive, so be patient)
• I searched for folders using the looking glass on the home screen (I could not navigate to the internal HD 'Documents' or 'Downloads' folder for some reason, but the search function was able to locate files)
• I copied the files onto the external drive, so nothing got lost
• I deleted the files from the internal HD, and subsequently emptied the 'Bin' so the space was cleared up
• I powered down the Macbook
• Used CMD + R to start the Recovery tool again
• Chose the option to re-install Big-Sur onto the Macbook
• Bit my nails for quite some time while the installation lumbered its way through loads of progress bars, but finally successfully completed the install. For extra kicks the 'less than 1 minute screen' staid up for a solid 10 minutes, making me think the installation failed again, but it went to the next screen (Apple logo with progress bar, no text) after a while.

It is a bit of work, but doing it this way meant I did not have to erase the internal hard drive completely, and did not even lose any files in the end.

Hope it works for you!

Oh, and also: Hey Apple, might be a good idea to warn users of the massive space requirement BEFORE they install the update, will save your customers some angsty moments :)

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.

I tried everything recommended I could find online without any luck. The only thing that worked was to factory reset back to Yosemite.

Here is the process I used:

1. Power Off the computer holding down the power button
2. Power On, and hold Cmd+Option+Shift+R after the chime (Internet Recovery Mode)
3. Open Disk Utility once recovery screen appears (will first be a rotating globe, followed by the apple logo and bar)
4. Erase SSD using Disk Utility > Rename to "Machintosh HD" (Format: Mac Os journaled)
5. Quit Disk Utility
6. Select Reinstall OS (Yosemite)
7. Go through the install process

From there you can update back to the OS of your preference. I will be avoiding Big Sur this time. I hope this helps at least one person.

GanJah wrote:

Im trying to install Big Sur on my macbook pro mid 2015 and it stuck at "Less than a minute remaining..." for about 2 hours now.. Should I just wait or is there something I can do?! Thanks

https://discussions.apple.com/content/attachment/1619bfa2-99b7-49b0-b4be-efda8e50b864

You can force quit a shutdown by holding the power button/TouchID for ~6-10 sec.

Reboot as normal and see where this leaves you.

https://support.apple.com/en-mide/guide/mac-help/mchlp2522/mac

Reboot and recovery mode is holding power button until power off, then hold CMD+r while power on. You will go into a recover mode screen where you can try to reinstall the OS on a specific drive, or roll back to a backup with TimeMachine (this crashed for me though).

I ended up holding ALT / OPTION while booting up, that took me to some boot mode allowing me to enter my old OS. From there i cleaned a lot of space, then ran the Big Sur installed again which worked (sort of).

Things that worked for me are:

1. Shut down by pressing power button

2. Then open the system in recovery mode. Press power button and then immediately press command + R button together to enter into recovery mode.

3. Then go to disk utils. Then select first partition named macbook HD (names may varry) . Run for aid check on toolbar.

4. Close the disk utils.

5. Then check for wifi connection if notconnected then connect properly.

6. Then restart the system.

7. After few time showing the apple logo screen. Finally it'll take you to the onboarding page.

I just hope it'll work for you.

I finally solved my problem by installing big sur on an external drive, booting from it, and accessing my internal drive files through terminal to move files to a separate drive and free up space. Once I freed up more space on the internal drive I was able to start the process over and reinstall big Sur on my internal hard drive without any hitches.

FOR GOD SAKE APPLE, Dont allow the freaking install to start if there isn't enough space to allow it to work. Seems to me that such a simple programming fix on your part could have spared me three days of extreme stress, a delayed delivery on the work I had to get done, and a whole lot of discontent aimed at your company.

Hi GanJah,

Thanks for coming to Apple Support Communities for help today with installing Big Sur on your Mac. The installation seems to be stuck.

You can try restarting or restarting in safe mode to see if the installation finishes or is actually finished: How to use safe mode on your Mac.

Have a fantastic day!

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?

An update:

The installation finished after leaving the new MB Pro on the less than a minute stage over night. Twice I had it sit on that screen for over 35 minutes. Luckily another poster mentioned patience. Obviously if you don't have room on your Mac's HD that is a different issue entirely.

So I managed to fix eventually, partly with luck though (and the post from Maddie above).

hold power to switch off, then hold cmd+r and power on again. you then get the recovery screen and I tried to reinstall Big Sur, but neither my HD nor Hd-Data had room, claiming approx 15GB and 400MB required.

I then rebooted and hold alt/option to boot into some secret magic mode that allows you to select your normal HD as the OS disc, and came back to my old High Sierra desktop. I then cleared lots of files onto an external drive and repeated from the cmd+r step above.

now the mad said I needed 4GB and 700MB respectively!! I repeated, and at my desktop I noticed the Hd disks NEVER reported more than 16GB total available, despite my moving files. I tried this cycle a few times and each time, the Big Sur install gave back random amounts of disk space required - this went up and down on each cycle and made absolutely zero logical sense - Apple, this is serious cause for me to move away from your products!!! Total rubbish.

I eventually decided to run the Big Sur update from my desktop again, since the recovery option would never allow it due to disc space, and it then ran fine as long as I selected HD-Data. It then updated fine, opened up Big Sur, and now reporting about 105GB free space!! Wtf right.

probelm now is I have an old HD (presumably with a High Sierra copy somewhere on it), an HD-Data (Running Big Sur) and an HD-Data-Data (for my Data) - total mess, so trying to figure out how to do a clean install (and migrate all my Lightroom & photoshop data!).

It works. But I am not happy with Apple at all. Total joke.

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 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.