Time Machine not working with Big Sur

In my case it hasn’t to do with Sophos as I don’t use it. I played a bit with the Time Machine settings and for the moment it seems to work as supposed. I removed the Time Capsule from Time Machine and added it again. That caused kind of a network crash. My Time Capsule vanished from AirPort utility software and after some time it reappeared. Now my MacBook runs backups on Time Capsule. It behaves a bit strange. For example if the backup is 100MB it runs the first 40MBs in seconds, then it comes to a more or less standstill, it takes minutes to reach 41,2 MB and then all of a sudden it is completed. I really don’t understand what is going on but at least it works. Maybe someone else can give it a try removing and re-adding Time Capsule from Time Machine and give feedback if that helps?

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.

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 have read through this entire thread and tried several suggestions. I verified I do not have the third party apps also mentioned. Time Machine will not work.

I have a Macbook Air 13 running on Big Sur 11.2.1. I use a Western Digital My Book external hard drive for my time machine. It has always worked. For years. And now I get nothing but can't back up due to errors.

I took the suggestion and using disk utility changed the format from APFS to Mac OS Extended. Somehow after the first time back up the container changes back to APFS and you guessed it - will not work.

What Apple voodoo is this?

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.

This is so aggravating. BigSur has been a ton of headaches so far (Bluetooth issues, kernel panics, mail app & exchange fails, and now time machine issues).

I tried the remove and erase and re-chose the back-up disk. 1st backup was fine, 2nd back-up was fine. 24 hours later, the error is back.

This is BigSur's issue...just like the horrible bluetooth lag that never existed on the same hardware with Catalina. Or the Mail issue, which is fine on my Catalina MacBook Pro but not on the iMac with BigSur. It's some of the laziest and most bug ridden I have ever seen from Apple.

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 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.

My Big Sur Time Machine backup drive is not working properly. Firstly message says It's full but I thought older backups were deleted to make room for new ones? Secondly when you open the drive in finder the previous backups are not visible?

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

I have a new MacBook Air (which is running Big Sur) and all my backups in Time Machine were from my older MacBook Air which was running an older version of IOS (High Sierra). When I enter Time Machine with the EHD plugged in to the newer MacBook Air, it doesn't show any of the older backups within Time Machine? Why is this so? Can this be rectified please?

Many thanks for any help given.

One possible issue you might check out. Big Sur has a plethora of ' enhanced' security issues- features. One must carefully check to see just what external disks/volumes it is allowed to connect to. Having spent a few hours in going from Catalina and external backup time machine disks to get Big sur time machine to accept and work, I eventully spent time going thru the security issues with hints and help from forums like this. Wish I could say go to xxxx in preferences and then to yyyy ,etc

but I did not document all the steps. So my comment is just a suggestion as to where to look. Some old macbook air ( I have one but did not attempt to upgrade to Catalina ) depending on date and may be able to give a few hints as to how to get to time machine- catalina- etc.