Time Machine backup on macOS Sequoia cannot be completed

Turning off the screen saver is not the solution. My never turns off. I manually turn off my monitors to avoid complications.

Here is what worked for me. I disabled the time machine volume and then reset it. No issues for me after doing this.

After purchasing all new USB-C to USB-C cables and reconnecting everything directly to my M2 mini and my M4 mini, Time Machine seems to be working perfectly since yesterday.

Try disabling your firewall and see. If it works you can refine Firewall by adding an authorization for TimeMachine.

I had a very similar error.

I hope it works.

I think you are on to something. I had a Find My widget tracking one person. After removing it, my backups have resumed as normal.

M1 iMac running MacOS 15.2

I have had similar problem.

I rebooted in safe mode and repaired the TM disk.

This seemed to help, but waiting to see if these "fixes" stick.

I was hoping that a fix would be available to us in the MacOS 18.1 release. Sadly, no. The failure of Time Machine backup to complete still is happening after upgrading my MBP M1. I've changed the frequency to Manual and am now requesting a backup when active on the MBP. Only then does it complete successfully.

Sequoia would not pick up my older hard drive from day one up updating to it.

I shelled out for a new DW Back up and set up Time Machine again from scratch. All working fine now.

The update must have screwed up my back up disc somehow? god only knows, it works now with the new one.

An update: I have followed with interest the many comments posted. I am glad several people have "fixed" the issue by deleting their TM backups, or deselecting and reselecting their TM destinations, etc. But clearly, many of us are still having issues of TM failing to backup when their computers have gone to sleep/hibernating, but works just fine while the computer and display are active. Many posts suggest this is an actual bug in Sequoia. I concur.

User Zoid85 suggested using a 3rd party app from the App Store called Coca, which I downloaded. When one of its preferences, allow display to sleep is checked, TM fails to backup. But when that preference is unchecked (thus preventing the display to sleep), TM successfully backed up several times over the past 24 hours, thus appearing to confirm the many posts that say that the issue is within Sequoia and permissions issues.

I plan to do some further testing to confirm. 1) I plan to check the Coca setting to allow the display to sleep and see if once again TM starts failing, and then subsequently unchecking it to see if TM backups normally again.

2) I missed a post by Chewbury who listed 3 terminal commands affecting power management. After I complete testing Coca, I will test his commands. Specifically, I will test all three as a group, then test them individually, one-by-one.

sudo pmset -b hibernatemode 0

sudo pmset -b standby 0

sudo pmset -b disksleep 1

3) An earlier suggestion was to "forget" the backup drive (a Synology NAS drive) in TimeMachine, reboot, and then reselect the drive. This has not solved the problem. I then took it a step further, I actually deleted the backup and the NAS share partition, rebooted, recreated the share and started a brand new TM set. After successfully completing the initial full backup, the backups failed (while I was under macOS 15.1) during unattended sessions. I then replicated this process when 15.1.1 came out (after trying the two suggestions above), and again after 15.2 came out. In all instances, TM fails to backup when the computer is unattended.

4) Someone suggested it was a firewall problem and to disable the macOS built-in firewall. I have never had the macOS firewall enabled, so that suggestion did not help. Instead, I use the firewall built into my Ubiquiti router. Even though TM worked just find under macOS 14 and macOS 15.0, once 15.1 came out, TM started failing while unattended. Even though nothing changed in my firewall rules, I explicitly created a rule allowing all connections between my 3 Macintosh computers (with known IP and MAC addresses) and my Synology NAS drive (with known IP and MAC address). This did not solve my problem either.

I appreciate all the comments on this thread, even though none that I have tried has solved my particular situation, and apparently not for many other people as well.

So, at this point I am at a loss. It definitely seems like a bug in macOS 15.1 and later. Apple needs to get more serious about identifying and fixing this bug.

It is a permission problem. The drive is set to Read Only. I spent many hours on this. With Apple Support and they failed to solve in including Safe Mode, and reinstalling the OS. no love there.

I had some sporadic backups completed. Most failed.

What worked for me (for a short time) was opening Time Machine settings and clicking the minus sign on the Time Machine Drive, and then adding it back.

However, I just checked and it is no longer backing up. When clicking on the "red i symbol" the error message is: Time Machine couldn’t complete the backup to (drive name) An error occurred while preparing the backup. It remained "read-only".

I have backups going back quite a long time and I am not going to wipe the drive. Health check is good. no errors found using Disk Manager. Apple is not good at software any more. Each upgrade in the OS is a downgrade.

My suggestion is reformat the drive for Sequoias file system APFS because HFS+ is no longer supported by macOS 15

MacLambh, thanks! That worked, logging off and back in. I hope it fixed it permanently.

I had this problem straight after Sequoia update. Time Machine would not pick up my drive.

I bough a new WD hard drive and it's working fine now.

Hope this helps.

This is not a permanent fix, but it works for me up until the display turns off:

Enter this into Terminal, and type your password:

"sudo tmutil disable ; sudo tmutil enable ; tmutil status"