Disk First Aid on Time Machine keeps failing

I'm getting the same issue:

Repairing file system.

Volume was successfully unmounted.

Performing fsck_apfs -y -x /dev/rdisk12s2

error: container /dev/rdisk12 is mounted.

File system check exit code is 65.

Restoring the original state found as mounted.

File system verify or repair failed. : (-69845)

In prior OS thru the years as a practice in maintenance I would occasionally run repair on all my disks including the system disk & Time Machine. All would go smoothly. I never had an issue up till now, with Big Sur.

My Time Machine drive is formatted with APFS. I reformatted the drive. Started over, and still it happens. I replaced the drive with a new drive and it still happens. Time Machine still seems to work. Though fortunately I never had to use it for a restore. Thus, I'm really not 100% sure it's working. :-)) Yes, I also backup with Carbon Copy with 2 separate copies. It's a great utility.

This is a bit odd, eh? Running repair with Disk Utility, should work. There's definitely, some issue and it has nothing to do with drives. I tried 3 different drives (including new) and the issue still persists.

This problem is specific to the Time Machine utility.

Király wrote:

Mac mini M1, MacOS 12.0.1

I got this error when checking my Time Machine disk (FW800):

Checking file system and repairing if necessary and if possible.

Volume was successfully unmounted.

Performing fsck_apfs -y -x /dev/rdisk11s1

error: container /dev/rdisk11 is mounted.

File system check exit code is 65.

File system verify or repair failed. : (-69845)

Backups were still running fine, but I erased the disk and started over anyway. A week later, same error. Backups still seem to run just fine. What should I do?

Why checking Time Machine...(?) is there other issues you are not stating?

I can say error messages—

"Time Machine has completed a new backup for you, or get a message saying it can't create the backup,"

or “failed to complete the backup, ” or “Preparing backup”

This message reappears most likely the TimeMachine disk is operating in a state of failure and will continue to fail with increasing frequency, in this case replace the drive.

You can erase/reformat/initialize the drive as new from DiskUtility and see if it sorts your issue.

3-2-1 Backup Strategy: three copies of your data, two different methods, and one offsite.

Trouble Shooting—

https://support.apple.com/guide/mac-help/time-machine-troubleshooting-mh15653/mac

I now discovered that only in Safe Mode, am I able to run Disc Utility (repair) on my Time Machine drive and not receive any error messages. :-)

If you are using a Firewire drive, then perhaps the hard drive is beginning to fail. You can attempt to check the health of the external drive by running DriveDx. Post the complete health report for the external drive here using the "Additional Text" icon which looks like a piece of paper. Usually "Warnings" and "Failing" notices on any of the health attributes indicates a worn out or failing hard drive respectively. If you are using an SSD, then it is best to manually review the health report.

Did you run First Aid on the hidden Container or just on the main volume? If you run First Aid on a volume, then attempt to run it on the Container, then First Aid will fail for some unknown reason. It is a very annoying bug.

It is also possible this is just a Monterey specific bug as well.

An alternative to Safe Mode is to create a bootable installer, boot from it, and then run the Disk Utility. Probably this is equivalent to booting into recovery assuming that the installer was created with the same version of the operating system.

I have bootable installers for (recent versions of) Catalina, Big Sur, and Monterey.

- Pie Lover

Oh cool, thanks 😊 Another good alternative to try! At present, although both are more time consuming as opposed to being able to go directly with the disc utility. Safe mode seems to work. Cheers!