Time Machine not working with Big Sur

I've been fighting with this for months, and finally found the cause (at least in my case): I'm running Sophos anti-virus, and this is a known incompatibility with their software and Big Sur which they have documented:

https://support.home.sophos.com/hc/en-us/articles/360051251412-Support-for-macOS-11-Big-Sur-

Here is the full description of the problem from their website:

"Time Machine backups to NETWORK locations (Time Capsule, NAS) are currently failing when Sophos Home is installed on Big Sur macOS 11 - Users will see a message reading "Time Machine couldn't complete the backup - The disk is already in use" This does NOT affect local backups, or backups to external devices/drives. 

This issue is currently under investigation by our development team. As a workaround, run the backup in Safe mode or use an external device to backup to. We expect this issue to be resolved by March of 2021."

I got a different error message (several of them, in fact), but otherwise this matched my problem description. In order to solve this, I had to completely uninstall Sophos. Disabling it wasn't enough. Hopefully they get it worked out, but in the meantime, I'd rather have backups than anti-virus (I'll experiment with other AV solutions).

Hopefully this helps someone else!

MarkChekal wrote:

I updated my 2015 MacBook Air to Big Sur.... and now, Time Machine does not work. I go to open it and it opens multiple windows and freezes.

By it do you mean the Time Machine app? Are you using the TM menu in the menu bar?

How is the LaCie drive formatted? I should be formatted OS X Extended (journaled) with a GUID Partition Map.

Since you haven't been able to get the first backup on the drive launch Disk Utility, select the top level of the drive in the sidebar and erase with these settings:

Then try backing up again.

1. Ok - for those of you struggling to get time machine to work after a Big Sur update - This is what I've tried and what finally worked for me.
2. Once I had updated my 2015 macbook to Big Sur I re-formatted my external hard drive to APFS - I've always used either G-Drives and Seagate (cheaper) - annoying as I lost all my old bkps - thanks apple!
3. I got to about 880GB of bkps when my G-Drive started making loud noises and either got "preparing backup" or "Time Machine could not backup due to errors" - thanks for the detailed error Apple!
4. I ran disk utility on all my drives including the boot drive in recovery mode. I also left time machine running all night while it "Prepared the backup" - still no joy - at this point I'm tempted to re-install Big Sur - but I can't because I don't have a backup of my user account because my old Catalina backup is no longer compatible! Thanks Apple.
5. I deleted some old large files on my macbook to free up space for the snapshots - still no joy. (Shame as really I wanted to back them up first)
6. Uninstall CleanMyMac X and Sophos (basically any anti-virus stuff) - reboot try again - fail
7. So I bite the bullet and buy a new 6TB Seagate drive (I'll definitely have enough space now!) and configured it as APFS - ran the backup and got to the same point about 880GB then Time Machine starts timing out again.
8. I keep hitting the backup now button for the next 72 hours but still get the - oh so vague - "Time Machine could not backup due to errors" - warning! Thanks for the detail Apple.
9. I decided that either my macbook's hard drive is corrupt or my external drive is corrupt - so I exclude the external hard drive from the backup and by hitting the options button in the time machine preferences and excluding that drive.
10. I still get errors, so this time I exclude my main drive. Bingo! Approximately 10 days after I upgraded I get my first backup but only fro my external drive one. Whoop.
11. Then I read somewhere that some third party Apps not found in the App store can cause Time Machine to fail - So I then go into a process of excluding folders from my my drive on my mackbook, first the "Applications" folder, then my "Systems" folder and finally "User" folder. If I exclude my "User" folder - the backup works! - Great I have a backup of everything except my own stuff!
12. So then I got through and one by one exclude each "User", until I discover my own "User" folder is the one that makes the backup fail. Thanks Apple - surely Time Machine could have told me this!!
13. Then I have a brain wave and decide to try and copy my "User" folder over to my external drive and sure enough the copying fails and I get a very specific error, that says something like "There is a problem with your Photos Library and cannot be copied" - Bingo!!
14. After a quick search I find how to repair my photo library - https://support.apple.com/en-gb/HT204967 and after a couple of reboots I get my first full backup of my laptop!

So to conclude, one of the things to try if your Time Machine doesn't work on Big Sur, if you have space on an external drive - try copying the files over manually first - to see if any of them are corrupt.

It's ironic that it was apple's own software 'photos' was the one causing me all the trouble.

I hope this helps someone and thanks Apple! It's great when it works, but when it doesn't - Arrrrrrrggggghhhhh!!!

MARCH 28TH - TIME MACHINE ISSUE,

What worked for me after upgrade from Catalina to BigSur 11.2.3

After several tries to use my previous Time machine backups or update them

I stumbled on what solved MY problem. YMMV.

A) https://support.apple.com/en-us/HT208050

Use zsh as the default shell on your Mac

Starting with macOS Catalina, your Mac uses zsh as the default login shell and interactive shell. You can make zsh the default in earlier versions of macOS as well. Goes on with link to instructions

B) Followed instructions carefully to change the default login shell to zsh !!!!

C) Shut down and rebooted computer ( I use a Mac mini (2018) 3 gz process 8 gb )...

D) ( I use 3 time machine backups - 1) Networked older 2014 mac mini, 2) an OTG solid state USB, and 3) an old WD MyBook media USB connected disk )

E) Plug in or network load each disk one at a time, run Disk Utility first aid on that disk - may take a while depending on each disk

F) AFTER each is " repaired " using Big Sur version of Disk Utility then mount/network to connect each disk one at a time

G Open time machine - select Enter time machine- backups should be available.

H) Then select Back Up Now .

The above sequence from E) on worked for me on all three different Time Machine disks

Other than having to re authorize a few applications- My upgrade to Big Sur took a few hours but went smoothly ( Used Ethernet connections and not wi- fi )

All,

I have experienced the same problem with Time Machine on Big Sur where as I was not able to complete my initial backup.

It was very slow and failed after approximately 15 minutes. My Time Machine backup target is a remote network drive that is formatted with the Apple Extended Journaled filesystem. I initially thought it was a Big Sur problem but I soon figured out that this was not the case because my wife's macbook air Time Machine was working flawless to the same network drive and with the same version of Mac Big Sur.

It was something specific configured on my Mac and I figured out that on my Mac Crowdstrike Falcon was installed by my company. This protects your system from Cyber Attacks and does some kind of AntiVirus scanning.

Anyhow, as a test I uninstalled this software with the following command:

sudo  /Applications/Falcon.app/Contents/Resources/falconctl uninstall

And guess what, Time Machine started working without any errors...

Of course I want to keep my system protected, but it would be great if someone else has found a workaround where both Crowdstrike Falcon and Time Machine can work together.

Just a small tip: Time Machine does not provide a lot of logging out of the box.

You can use these commands below in a terminal to get some more real-time debugging information when you are troubleshooting Time Machine.

sudo tmutil logging --debug

log stream --predicate 'subsystem == "com.apple.TimeMachine"' --info

Boot into Safe Mode by booting with the Shift key held down and check there to see if the problem persists.  Reboot normally and test again.

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

In fact this (removing Sophos) did not prove to be a long-term fix. I started to experience other issues with Big Sur when copying files (file transfers stuck), when booting up (incredibly slow) and Time Machine. In the end the only solution was to download the Big Sur installer, create a USB installer disk and do a totally fresh install to the Mac's SSD. I then restored everything from iCloud (not TM) to avoid copying back any problems. Photos took a long time to rebuild but it is now 100% stable.

Quick update on this issue:

I was still getting the “Time Machine can’t backup error” and I am now pretty sure is was because my apple TV was using a ‘photos’ folder from my laptop to run a screensaver slideshow. Anyway since I’m paying for iCloud storage to backup my photos anyway, I’ve decided to exclude the ‘photos’ folder from the Time Machine backup altogether. Apparently sharing a ‘photos’ folder across a wifi network is some sort of security issue for Time Machine – even when I’m securely logged into two APPLE products… eeesh. Good new is my new seagate drive is a lot quieter than my old drive and I finally have stable hourly backups running with no issues.

I had experienced the same problem when I upgraded to big sur. I fixed it by removing the Sopho Home from my Mac. I suggest if anyone found the time machine is not working on big sur, try to remove the anti-virus then restart the mac and try again. If the problem can be fixed than try to looking for another anti-virus software.

With LaCie drive. Not working. Used DiskUtil to partition drive. I made current partition just above current size (about 700G). Made new partition with the rest of the space (about 1.3G) (sT drive). Ejected drive, rebooted, attached drive and changed Time Machine drive to new partition. Waited for backup to start and it completed "Preparing to Backup" and started a complete new backup (very large). Hope this helps. Old backups still on other partition. Will continue to use new partition for Time Machine.

I read a couple of conversations in discussions.apple.com & also an apple article. Both triggered me to try this and worked for me. Perhaps for you. I went into Time Machine and Removed the backup drive where you can Add or Remove. Then I Added back again. My backup finished as they had in the past. Hope it works for you AND continues to work for me.

I don't have a definitive solution, but only an (anecdotal) partial solution which may help in some cases. After upgrading to Big Sur 11 four weeks ago I was unable to get TM to work at all, despite trying most suggestions in this thread and elsewhere. Back-ups would get stuck on "preparing" and occasionally get past that point then get irretrievably stuck about 25% to 50% through the back-up.

Summary: Using the System Preferences/Time Machine I unselected the target disk, disconnected it from USB, reconnected, then reselected it again and tested it. Initially it made no difference. However, following some advice I did this back-to-back several times, and on the 4th or 5th time something "clicked" and it promptly did a quick back-up. Its still working but has regressed somewhat. It backs up regularly, but on-screen it goes through the process and gets about 50%, when it pauses any visual progress for about 5 - 10 minutes. At this point it jumps to "Cleaning up.." and apparently completes/closes. It shows a finished back up, and this can be accessed by TM. I have checked some files I am working on and they appear to be backed up OK; but I can't yet be certain that its failing to back up some other files?

Detail context: MacBook Pro 15 2014. External disk WD My Passport 2TB (HDD). This was initially formatted HFS+, until out of frustration I binned the existing TM folder and Time Machine took that as an invitation to reformat the volume to APFS (it remains APFS). Ok, and it created an initial new back up with no problems, actually I found it very quick considering it was 400+GB. It then immediately went back to getting stuck on "Preparing...". Until I did the above.

Hoping to avoid these little problems I had done a clean OS installation (Macintosh HD internal erased, reformatted and new OS install), new app installs, plus manual transfer of data. I also initially suffered from the reported Bluetooth drop-out problems but this seems to have been solved for me since the 11.2 update.

My next move will be to change to a SSD. Apple says the older HDD should still work OK (HFS and APFS) but other commenters see problems and are not enthusiastic. e.g. Bombich at Carbon Copy Cloner, who doesn't recommend them any more (for his back-up software). https://bombich.com/kb/ccc5/choosing-backup-drive

I have a 6 GB rotational drive from OWC that's formatted OS X Extended Journaled and have no problem with Big Sur.

However, I did have a problem with the drive in Catalina experiencing the same "preparing backup" that you did. I eventually had to erase the drive and reformat the same. It's been running without problem since.

I didn't have any files on the TM drive that were not on my boot drive so I don't lose any files in the process.

Sophos Home AV seems to be blocking Time Machine updates to Network volumes at the current time:

https://support.home.sophos.com/hc/en-us/articles/360051251412-Support-for-macOS-11-Big-Sur-

Thanks to everyone. I haven't been able to back up since the initial November release of Big Sur. I called Apple Support a couple of times and have tried several suggestions I found in Google searches with no luck. I only had Sophos Home disabled. I should have tried uninstalling it but didn't think of it. After doing that, back ups appear to be working fine again. Thanks for the link to Effective Defenses... without 3rd party software. I look forward to reading it.