Target disk mode -big sur

Ermintrude75 wrote:

I've looked at that. It doesn't address the issue I am having.

my MacBook is compatible.

I have enough memory.

I can download the installer.

At about 10 mins left it tells me there is a problem. I click ok and it gives me the greyed out option of restart or Target Disk Mode.

If you have the full installer sitting in your Applications folder "Install macOS Big Sur.app"

The reboot into Safe Boot mode and from this environment, try launching your the installer.

SafeBoot https://support.apple.com/en-us/HT201262

Takes noticeable longer to get to the login screen, does a 5-15 minute disk repair before it fully boots up, and certain system caches get cleared and rebuilt, including dynamic loader cache, etc. Login and test. Reboot as normal and test as caches get rebuilt.

In Safe mode third party system modifications and system accelerations are disabled, it removes malware, etc hampering smooth operation, however a reboot will put it back to normal mode.

All good :) Happy to try and help.

Disclaimer: this was all new to me as well. I was simply following some steps seen online, so approach this at your own risk. It was a last resort for me, so don't go on from here unless you feel it's worth the risk.

Here's the main forum I referenced when looking into this - https://apple.stackexchange.com/questions/197503/how-can-i-delete-files-in-recovery-mode-using-terminal-on-my-os-x-main-partition.

To start, head back into Recovery Mode. Under the Utilities menu, you'll find Terminal.

I'm assuming you have verified that a lack of storage was likely the issue by following the steps I mentioned previously, so your goal now is to locate something on your drive of sufficient size to delete and free up space for the update to complete.

Start easy. Type in cd /Volumes then ls to list all mounted volumes. Hit enter after each command. You should see something like Macintosh HD and Macintosh HD - Data listed, and possibly others. Macintosh HD - Data is typically where your files are located.

If you're not familiar with exactly how the directories are set up, you can use the ls command again to look around. For example, if you want to see all the Users on your drive, type in cd "Macintosh HD - Data/Users/" followed by ls to see a list of the Users. You can then use the same pattern to slowly move through your folders and find something to delete.

A couple of tips if you run into trouble:

1. Make sure to have the opening and closing " with each command. Without this, the spaces in the volume names will screw it up and the command won't be recognized.
2. Also, try the long-form commands in full and test things with and without a / and the beginning and end of the commands. I can't recall the exact pattern that eventually worked for me but I know I messed with this a bit before I figured out what I was missing. When I say long-form, I mean without the shortcuts - in case you try a command that doesn't work along the way. For example, always include /Volumes/Macintosh HD - Data/ when going deeper into the directories, even if it may not be necessary each time.

So you might try commands like cd "/Volumes/Macintosh HD - Data/Users/<username>/" and cd "/Volumes/Macintosh HD - Data/Users/<username>/Downloads/" where <username> should be replaced with your Mac username. If unsure of your exact username, use the command I mentioned earlier to see a list of Users.

Up to this point you're simply navigating around your drive - much like you would in Finder - the only difference being you're typing it all in and not using a nice UI.

From here, it's important to make sure you're in the right directory because the commands get more serious when you start deleting things. I can't stress this enough - only delete things you are 100% sure are safe to be deleted. This is a permanent deletion - there is no Trash to recover it from later. If anything looks remotely like a necessary system file, stay clear of it. I do not know what the ramifications could be if you delete something important. You shouldn't really come across anything like that if you're in the place of Downloads, Documents, Photos, etc. but it goes without saying to be extra careful. If you don't feel comfortable deleting things, I'd suggest finding a professional to help.

If you believe you are in the right directory (use the ls command as much as you want to make sure) then you can move to delete something using the rm -r or rm -rf command (see forum link for the differences between the two).

For me, I knew I had a large (10GB+) zip file of Photos that I had neglected to delete in my Downloads folder so I used cd "/Volumes/Macintosh HD - Data/Users/<username>/Downloads/" and then listed everything in it using the ls command. I scanned the list it gave me, looking for the name of the zip file - Photos. I found it so knew I was in the right place. Without leaving the Downloads directory, I typed in rm -rf Photos and hit enter. And away it went.

It may look like it didn't do anything - if I recall correctly, the Terminal sort of briefly flashed to indicate something happened. The best thing to do is use the ls command again to give a list of the directory in its current state and see if the file or folder you chose to delete is now gone. Repeat this until you feel like you've freed up enough space to complete the update. It's impossible for me to say how much you need to delete, I would just suggest you rid of as much as you can safely. I suspect my 10GB+ file was more than enough and you probably don't need that much but it's impossible to say.

Once you feel good about it, it's time to let the update try its thing again. For me, it was as simple as exiting Terminal and restarting the Mac under the Apple menu. It cycled back to the 29-minute countdown like it always had been but this time it kept going all the way through to a successful completion and reboot.

I was having a similar issue to others in this thread but I didn't get lucky like the OP. Full story below, but in short, Apple Support was no help to me and using a combination of booting into Recovery Mode and commands via Terminal was the solution to making space for the update to complete successfully.

Long version...

I was stuck in a cycle starting at 29 minutes where it would get as close as 5/6 minutes left before erroring out and giving me the same options: greyed out "restart/reinstall" option and then the option to go into Target Disk Mode. After 2 days of researching and a couple of hours with Apple Support on Chat and Phone, came to the conclusion that there wasn't enough space on the drive to complete the update so it was just stuck in this cycle. Why it doesn't make sure there's enough space before starting, I don't know, but that's what it came down to.

Apple Support's only options were to try Target Disk Mode or erase the disk and start over. I didn't have a Time Machine backup and though I had my most important files backed up elsewhere, I wanted to avoid wiping the disk. I tried Target Disk Mode, which worked for about 15 seconds before cycling back into the same routine starting over at 29 minutes again, and ultimately failing each time. So I didn't have enough time via the other Mac I hooked up to get into the files and delete anything to try the update again.

I took to the web to see if there were any last options to avoid erasing the disk and losing all my data. There is! I restarted the Mac and got it into Recovery Mode. After checking available storage in Disk Utility, it was clear that lack of space was likely the issue (only 15MB free). Here's where Terminal comes in. I was able to use some "basic" text commands to locate a couple of large unnecessary files in my Downloads folder, delete them, and then restarted the Mac again. It went back through the same cycle - starting at 29 minutes left, but instead of getting stuck, the update completed and I'm back in business without losing any data.

I say "basic" because it was all brand new to me but I made sure not to do anything too risky. And read multiple forums out there before trying anything.

So...if Apple Support is telling you to erase the disk, and you don't have a backup of everything...all is not lost. You need to be comfortable trying things in Terminal which can be a bit offputting to folks. But I was down to my last resort and ready to erase the disk, so it was worth a try for me.

If anyone is in the same position and down to their last resort, let me know, and I'd be happy to walk through the steps I took in more detail.

I feel you. I too am not experienced in these, though I guess now I know something new having gone through this!

Safe Mode and Recovery Mode are two different things. I was unable to boot into Safe Mode when trying with Apple Chat Support. To get to Recovery Mode, first restart the Mac - you can do this either by clicking ok to go into Target Disk Mode or under the Apple logo in the top left of your screen. As soon as it powers down, hold down Command + R at the same time while restarts. Keep them held down until the Recovery Mode appears on screen.

From here, you should have four options in the main window. It should look like the screenshot here - https://support.apple.com/en-us/HT204904. These are the steps Apple Support was able to talk me through.

If you have a Time Machine backup, you can do that here. I did not, so I attempted to Reinstall MacOS. I was unable to do that too though, due to lack of space on the drive. You can go through the Reinstall steps here to try it first if you like - mine wouldn't let me past the screen after you accept the T & Cs and told me I needed another 12GB of space to reinstall. (Thought to myself, if I had that space, I wouldn't have been in this situation! If you run into the same thing, you likely have the same problem I did. You can verify the space available on your drive by using Disk Utility - it will look like the screens here - https://support.apple.com/en-us/HT210898. You want to check to see what your Free space looks like in the Internal drives.

If it looks like you're low on space, then you're likely in the same spot I was and would need to go into Terminal to try things there. But go through the above steps first and let us know what you find out.

Here are the commands I used to do this: I used Recovery Mode (Restart and hold down Command-R) to get into Terminal Mode (an option from the menus on the Recovery Mode Home Screen). I used the "find" command (find / -name Downloads) to locate where the system might have some unnecessary files. I used the "cd" command to change to that directory (cd [and then insert the file path you identified using the previous find command] ). Then I used "find" to single out large files (find . -size +100M). I used the “rm” command to get rid of unnecessary files (CAUTION: do research on how to use "rm" if you haven't used it). After that, I went up a level using the "cd" command (cd ..) and used the "find" command again but this time I looked for larger files (find . -size +1G). I was able to identify podcast videos that were 1.5-2 GB each. Once I deleted all of those (using "rm"), I had a ton of free space. I restarted and the OS upgrade was successful.

Maybe I can help, i managed to do it with some easy steps. Open terminal and then first type: ‘ls -la’ without the ‘’

that shows you in what directory you are and what folders you can choose from. I saw like 5 folders and they had names but 2 also didnt have names, it just said .. or . So 2 dots or one dot. Turned out I had to go into the one dot. So I typed: ‘cd .’ Without the ‘ ‘

cd = change directory and the dot is where I had to go. Then nothing happened, so i knew it worked, otherwise i’d get the same error as you, like no such directory. Anyway, now you type ls -la again to confirm you went into the dot folder. Then i saw like 20 folders, including system, volumes etc. So i went into volumes to get to my HD. Keep repeating ls -la to make sure you are going the right way. The only stupid thing is you cannot type spaces. But my HD had spaces in the name, for example ‘HD of John’. When I typed ‘cd hd of john’ it would give an error because a space is a new line, so it would try to go into just HD and that folder doesnt exist. I found out I had to use this sign \ after the space

that shows the pc there is a space, so now it became: cd hd\ of\ john

it worked!

finally i saw my HD and from there I went to user > my user name > There i could delete whatever of my folders I wanted with the deleting command ‘rm -R (name folder)’ without the ‘ and (

then i kept checking if it went well by typing ls -la and indeed, the folders were dissapearing.

i hope there is something in here that will help you, I’ve spend more than 12 hours on this crap and I’d be glad to help someone else save that time. This was all brand new to me, I’ve never used terminal or anything but I managed to do it so you can do it too.

I am literally spent after spending the last day and a half doing remote IT with my daughter, who lives 1500 miles away. The Big Sur upgrade (which I have abbreviated to BS...pun intended!) was required by the online exam platform she is required to use and had to be done this week. Long story short, only with the help of the article by Mr. Macintosh, link below, were we able to unlock her encrypted data, finish the BS install, and get her MacBook air up and running again perfectly.

Before upgrading I had her check all of the Upgrade requirements, and her MBA met them all, including having enough storage to do the upgrade, but only just at 49GB. The Apple website only mentioned needing 35.5, so I figured she was golden. The upgrade seemed to go okay, but then we ended up in the "Error Occurred" loop mentioned in the article.  

I spent hours researching on Apple Support Community and Discussions. The only “solution”  I found was to restart the computer, which, of course did not work. I googled again and came across the Mr. Macintosh article, link below.

I want to encourage anyone else with this issue: do not freak out, all is not lost. If I can walk my IT challenged daughter through this via the telephone with ultimate success…no data lost, you can do it too…but only with the help of Mr. Macintosh!

https://mrmacintosh.com/big-sur-upgrade-not-enough-hd-space-serious-issue-possible-data-loss/

It was my storage. I even took it into the Apple Store and they wanted to charge me to do the upgrade. I rebooted the whole system, deleted unwanted data and had success with the upgrade.

HI, I am having the same problem with the Big Sur upgrade.

Each time I try. It kicks me into Target disk mode. It gives me the greyed out option of restart or Target Disk.

When i restart it starts at 29min remaining and goes through the whole process again.

Thanks for teh reply. I have tried to restart (5 TIMES NOW) in safe mode but it goes directly to the reboot (29 minutes) and ends with that same screen. It wont let me action anything on the computer - i cant even check my memory.

Any suggestions most welcome please?

Hi, wonder if you had any success. I have exactly same issue with reboot at 29 minutes then at 22 minutes going to “an error occurred applying the software update” and after pressing “ok” goes to “choose startup disk” screen/target disk mode. Thanks!