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Since upgrading to OS 15.1.1 my Time machine will get to about 80% then stop with the message "time machine could not complete backup because some files were unavailable. I've restarted with another drive as SU and run First Aid but same problem. From what I've seen here this is a bug in 15.1.1 and nothing can be done until Apple issues a fix. Or is there a workaround?
Mac mini (M1, 2020)
Since the update to macOS 15.1.1 i also have this problem.
If my MBP and External monitor goes dark (Lock Screen) and after some time I come back to my machine it states "Time Machine Backup could not be finished".
Sleep is disabled, because I have other programs running with which I don't have any problems, they keep running as intended.
System Settings > Battery
Before 15.1.1 Time Machine worked even if the displays were turned off.
If I use my MBP the backups will complete just fine..
Since the update to macOS 15.1.1 i also have this problem.
If my MBP and External monitor goes dark (Lock Screen) and after some time I come back to my machine it states "Time Machine Backup could not be finished".
Sleep is disabled, because I have other programs running with which I don't have any problems, they keep running as intended.
System Settings > Battery
Before 15.1.1 Time Machine worked even if the displays were turned off.
If I use my MBP the backups will complete just fine..
grantjeffries wrote:
Since upgrading to OS 15.1.1 my Time machine will get to about 80% then stop with the message "time machine could not complete backup because some files were unavailable. I've restarted with another drive as SU and run First Aid but same problem. From what I've seen here this is a bug in 15.1.1 and nothing can be done until Apple issues a fix. Or is there a workaround?
I am not familiar with a TM bug in 15.1.1
What I can say—
This is one of the classic error messages when a drive is working in a state of failure:
Time Machine has completed a new backup for you
can't create the backup
failed to complete the backup
an error occurred while preparing the backup
If you continue to get these errors I would suspect the Time Machine drive is starting to fail, the answer would be replace the drive and /or try another drive and compare your results..
Time Machine troubleshooting on Mac
Time Machine troubleshooting on Mac - Apple Support
If you value your user data
3-2-1 Backup Strategy: three copies of your data, two different methods, and one offsite.
More than one device, more than one backup methodology.
This is an Apple defect that has several variations and workarounds found by the boards. Apple has not offered yet any credible solution or explanation. Apple support and engineering know this from mid-October but nothing has been offered as a solution. The support team at Apple will insist that you upgrade and call them back if it does not work. It won’t.
The defect in the last three versions (at least) of Sequoia: 15.0.1, 15.1 and 15.1.1 makes TM backups fail with either “Files not available” when the backup is about to end, or ”Hard disk was disconnected” fairly quickly after starting the back-up process for NAS locations and local (hardwired) hard disks.
Check the threads:
I have 15.0.1 on a MacPB M1 Pro. The workaround I found in the boards that works for me is to turn off the MacOS Firewall (System Settings > Network > Firewall). The TM backups complete without errors. It appears that it does not work for everyone but it is worth a try.
This is the error that I get
It isn't just you and likely not a drive failure. I'm having the same issue that started with 15.1.1. Basically it complains that it couldn't finish the backup because some files were not available and to try again when logged in. I think it has to do with the screen saver being active. If you don't let the screen saver start it should finish the backup. It happened in some minor release a few years ago and they eventually fixed it.
Yup, that is the key. "When your Mac is unlocked". It is some bug having to do with your screen saver being active. Probably disabling the "require password to unlock screensaver" option would mitigate it for now, but then, security...
Another thing that comes to mind. Did you enable "sleep mode" on this Mac? This issue has come up with some folks with this mode enabled during an active TM backup.
That is: System Settings > Energy, and check the following two settings:
To prevent sleep, the first should enabled, and the second, disabled.
Lastly, the issue could also be due to files on the internal drive. Have you recently tried running Disk Utility's First Aid booted up in Recovery Mode on your Mac's internal drive?
If you're up to getting into the details of a Time Machine backup, I suggest you consider the following free app from The Eclectic Light Company: Time Machine Mechanic
It basically reads the macOS logs that pertain to the TM backup process so that you can get an idea where the process fails to complete. This could provide you with some clues on where to start troubleshooting. I do; however, concur with leroydouglas that the backup drive may be the culprit.
time machine could not complete backup
