Update to macOS Big Sur 11.1 from 11.0.1 fails

Boot into Safe Mode by booting with the Shift key held down and try the update from there.

NOTE: Safe Mode boot can take up to 10 minutes as it's doing the following; =

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

Safe mode had no bearing on fixing this. Tried SMC and nvram resets with no luck.

Wound up downloading and applying MacOS Big Sur 11.1 from the app store. All is well now.

I think I had an issue with com.apple.os.update being undersized after applying Big Sur 11.0.1

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I am seeing a similar issue on a 2019 iMac 27"5K. The update downloads and starts the preparation phase which stops after 5 minutes or so with a popup saying the download failed. The dialog in the box says to check the internet connection. After checking that two internet connections are okay, repeated attempts also fail.

Doing a disk first aid on the update com.apple.osupdate volume says there is an issue with the allocation.

Stuck here.

Identical issue on the same configuration. 4th time downloading a 3.27GB file...only for it to fail due to the internet connection (which is fine), even after the file has fully downloaded and is 'preparing'.

I've tried to download that a couple of times also, unfortunately with the same error message either 'download failed' or 'installation failed'. It hasn't yet completed the download.

What is most frustrating is that I can download the whole 3.27 gig update file (where does it go!) yet when it get to processing it for installation the 'download failed' error occurs - even though it's already completed the download. I've done this 4 times now, trying different solutions including safe mode. It won't pick up from a downloaded file and starts from zero each download.

Yesterday all my desktop icons disappeared, I have a sneaky suspicion this is something to do with iCloud credentials or certificates. The log files show "The connection to ACDAccountStore was invalidated"....

Same, safe mode makes no difference for me either. I also signed out of iCloud and back in to see if it was a credentials issue, all that did was give me another 138GB download as it restored the desktop and documents folders unnecessarily. Oh, it also removed the ability for my Apple Watch to unlock the iMac and I'm not doing it again just to have to download files for 12h.

I also discovered cloning the disk (can you tell I'm getting nervous?) doesn't work either, due to a 'broken seal'. This seems very beta to me right now.

I had the same problem of failing at 10 minutes. My MacBook went through just fine. Not my MacMini. So I finally booted in safe mode and installed the update. All went fine. I wish Apple would jump on-board and make suggestions that may work, or better yet fix the updates.

I have the same issue. Macbook pro Late 2013. The installation stalls at 15 minutes even in safe mode. Big Sur for me has been a big pain in the ***. Downgrading to Catalina and hoping for the best. My computer was working flawlessly, now it is slow and has memory swaps all the time. Very annoying.d

I am in the same boat where nothing seems to be working around the failure noted. My MacBook Air downloaded and installed 11.1 without a hitch.

As has been noted I am not interested in doing a new install of Big Sur from the App Store.

Has anyone heard of Apple answering on this question?

Thanks sikeer666 . I’m afraid this hasn’t worked either. I do think we shouldn’t be having to go through all this palaver and that Apple should fix the update so it can be seamlessly installed. There is clearly a problem with the update if so many of us are having problems. I don’t think I can do anything else so think I will have to wait for a fix for this.

And further to below I have just read that indeed it is a know problem and next update should be a fix for it ... https://appleinsider.com/articles/20/12/18/macos-big-sur-update-bug-is-causing-issues-for-mac-system-administrators

I’ve just tried again standard and in safe mode . Same think ... downloads fine sticks at installation then after an hour or so error message instillation could not be completed. I’m at a loss and not technically able enough to interfere more!

Hey There, So I read in an Apple Developer Forum from user BenHaith that if you download Big Sur from the App Store it should work! It took a while but was able to install the new software update. Hope this helps!

I had a tiny 36 GB external disk partition as a Big Sur test-bed with only 9 GB free space. The v11.0.1 to 11.1 update repeatedly failed there during the last two days. I then used Carbon Copy Cloner to clone that to a bigger 64 GB partition and then the update succeeded.