Same!
I was stuck today with this issue updating to 11.5, all progress halted with 15 minutes remaining in "preparing the update" after it had downloaded. No amount of restarts worked, however booting in safe mode did work and allowed the update to complete.
currently on the 11.0.1 BIG SUR on MacBook pro 16inch early 2020 - trying to update the software since a week now... Anyone from APPLE willing to follow up here ?
Hello, i'm no expert but here's the solution i was able to come up with (keep in mind it's still going to take a while, but it should still work):
-Boot into safe mode -(restart computer then hold Shift until prompted to login)
sudo nice -20 softwareupdate -i -a --force --verbose
(sudo for privileges, "nice -20" for highest priority (probably doesn't change much but makes sure it's regarded as the top priority))
I hope this helped, this was the only think i was able to get to work for me
Refer to my answer (might be in the very back) i hope this helps.
I had the same thing happen to me. The download doesn't progress after it hits 10 mins remaining mark.
Here's the solution:
Good luck guys! :)
Hi Apple, what's going on here? Can not be true that such huge BUG can not be fixed immediately... Wanna downgrade to Catalina again and wait for healthy macOS 11.5.1
I believe the issue is that these software updates, like Time Machine backups, are given a low CPU priority, so they can take a very long time if there are other, higher priority foreground or background processes running simultaneously. It can be sped up with a Terminal command that temporarily disables low priority process throttling:
sudo sysctl debug.lowpri_throttle_enabled=0
This change is reversed on reboot or by entering this Terminal command:
sudo sysctl debug.lowpri_throttle_enabled=1
I think this is why some people have found success with updating in Safe Mode, because unnecessary processes would be disabled.
Upgrading to Big Sur 11.6 the process was stuck at Preparing Updates 10 mins remaining. I removed Sophos Home and rebooted the computer and update worked fine after that.
Guys,
It is not a bug or anything, it is the fact that if you are using VPN or there's any firewall in the network you are connected to, the installer won't be able to connect to some apple download servers (on certain ports) to download necessary sources.
I tried multiple times to update from 11.4 to 11.5 and then 11.6 to no avail in the office. Safe boot, restarts, App Store, etc. didn't help at all - it got stuck at "10 min remaining" for ages. I got 2 and 2 together when I read that some of people killed sophos (which filtered network traffic and probably ports) and I also knew my office network has VPN behind and NATs to allow access to remote infrastructure. So I went home and tried the same thing, no restart, no safe boot and - boom, no problem updating.
Try performing the update in a NAT, VPN and firewall free network, and update will go through, I am writing from a big sur 11.6 at the moment.
Good luck!
I received a "Failed to prepare the software update. Please try again." message while trying to update from Big Sur 11.8.5 on an M1 mini. If would run for 10 minutes then stop with that message.
I reloaded the software to try a total reinstall, but I also saw an error message on my system preferences. When I went to system preferences I saw a message that I needed to provide my iPhone 6 digit passcode to allow unified security.
Once I did that the update ran all the way.
Maybe related or may be a possible solution.
Has been 2 years yet it's till isn't fixed, can't believe Apple isn't fixing a big bug like this