Time Machine couldn’t complete the backup to “TimeMachine”. An error occurred while preparing the backup

I am now on my second iMac in 3 months. The first one had the time machine issue out of the box- had to call the first day I had it. I spent hours and hours troubleshooting over a few weeks- on the phone with apple, different cords, new drives, reinstalled the OS, etc. That iMac became an insane nightmare to the extent that it was crashing every 5 minutes. I just got my replacement. Used a brand new drive to run a time machine backup, managed to make one and I'm right back to the error message about not making another backup-- error occurred while creating the backup folder. Ultimately, I was told it is some kind of bug in the OS and I just have to wait. I am so disappointed in Apple. This is such an important part of my data management as a professional photographer. This has been going on for months and they still have no fix. They need to stop rushing to get these OS upgrades out without testing them enough for issues. The upgrades have become more and more troublesome over the years.

No worries.

If you decide to run the command to clear Time Machine snapshots, just disable auto backup in Time Machine Preferences first, you can also eject the external drive, sorry, it’s not imperative but I left that out, but one of those steps should work, cheers.

Good luck!

True, it is hidden by default. Just open Finder, While holding Option on the keyboard, click Go on the top menu and choose Library, (About half way through the menu). As long as you hold down Option, the Library will show.

So you can:

Quit Safari.

Save then delete ~/Containers/com.apple.safari.

Restart Mac, and launch Safari again to re-create the corrupted file, and try backing up again. Worth a try anyhow.

thanks ... but

cables & usb ports are working fine with these and other disks

all files being backed up are local (no cloud etc)

I have excluded dropbox and another folder that I regularly download to

Did a OS update so now have Big Sur 11.5.2

when the disk is first formatted it seems to do 1 full backup then every time it tries to do the nest auto backup it gives the failed message

when I enter into Time Machine it weird because it show incremental backups on the right of the screen

I am now doing some tests (by creating new folders & files ) to see if they actually do get backed up

Amazing, well done! Too bad though, that’s an awesome record! How could Iggy do that to you!? 🙂.

Just curious, about the logs, did you search Console system log? Or open it in /Library/Logs or ~/Library/Logs?

Nice job finding that, hope you can download it again without issue!

Thanks for your note. I don't know about the exact formatting, but until this last Monday I was running Mojave, upgraded from perhaps Sierra (??) before that. I'm running a Mid-2015 iMac and the external drive (MyBook for Mac) has backups back to 2016. What you note is basically where I'm at. I have a new external drive arriving Friday and had just planned to start over (so that I didn't eliminate a restore option by reformatting the old disk). What is giving me pause is that if there's some other glitch in the Big Sur installation and I get the same error with the new disk, then I'm out $180 for no reason. That's why I'm wondering if this "removing snapshots" recommendation is worth a try before tearing open a new disk. If I have to do a restore to Mojave and then re-install Big Sur to get TM functioning, I need that MyBook backup not to be corrupt (BTW, I can enter TM and see the backups as usual, just can't get it to make a new backup). Any thoughts will be most appreciated. Thanks.

Thanks for all the help. I'm way out over my ski tips on this one. . .

I tried a backup and copied the log. It is quite long, so tried to paste below where it appears to start to go wrong. I've removed the name of my computer and replaced with XXXXXXX. Otherwise this is exactly as it appears. I'm going to try the other steps this weekend, but wondering if any of the following sheds light on the issue:

2021-09-09 21:37:04  Cached event database was unreachable at /Volumes/My Book for Mac/Backups.backupdb/XXXXXXX iMac (79)/2021-09-09-213658.inProgress/C309C9CB-6C9A-4A34-933E-01F603BB81A8/.87EB482A-B6F5-3F9A-9C2A-FD1E652BE9C9.eventdb

2021-09-09 21:37:04  Possible strategies for "Macintosh HD - Data" (device: /dev/disk2s1 mount: '/System/Volumes/Data' fsUUID: 87EB482A-B6F5-3F9A-9C2A-FD1E652BE9C9 eventDBUUID: E59C3A04-F682-4779-BB78-0AD01E37922B) (<EventMarker 2021-09-06 20:59:35 +0000 75743201 E59C3A04-F682-4779-BB78-0AD01E37922B 0>): first backup, deep scan, FSEvents,

2021-09-09 21:37:04  Using FSEvents for source: "Macintosh HD - Data" (device: /dev/disk2s1 mount: '/System/Volumes/Data' fsUUID: 87EB482A-B6F5-3F9A-9C2A-FD1E652BE9C9 eventDBUUID: E59C3A04-F682-4779-BB78-0AD01E37922B)

2021-09-09 21:37:04  Read 0 clone families from /Volumes/My Book for Mac/Backups.backupdb/XXXXXXX iMac (79)/2021-09-06-174437/.87EB482A-B6F5-3F9A-9C2A-FD1E652BE9C9.clonedb

2021-09-09 21:37:04  Buffering events...

2021-09-09 21:37:04  Unrecoverable zero fileid - path: 'Users/XXXXXXX/Library/Containers/com.apple.Safari/Data/Library/Caches/com.apple.Safari/WebKitCache/Version 16/Blobs/97829D2F9B149F4B0DBD93B1D000E22F51831C81', flags: 00100200

2021-09-09 21:37:04  Event collection stopped because of error: Error Domain=com.apple.backupd.ErrorDomain Code=303 "(null)"

2021-09-09 21:37:04  Failed to collect events for "Macintosh HD - Data" (device: /dev/disk2s1 mount: '/System/Volumes/Data' fsUUID: 87EB482A-B6F5-3F9A-9C2A-FD1E652BE9C9 eventDBUUID: E59C3A04-F682-4779-BB78-0AD01E37922B), error Error Domain=com.apple.backupd.ErrorDomain Code=303 "(null)" UserInfo={FailedStrategy=16}

2021-09-09 21:37:07  Unmounted local snapshot: com.apple.TimeMachine.2021-09-09-213702.local at path: /Volumes/com.apple.TimeMachine.localsnapshots/Backups.backupdb/XXXXXXX iMac (79)/2021-09-09-213702/Macintosh HD - Data source: Macintosh HD - Data

2021-09-09 21:37:07  Mountpoint '/Volumes/My Book for Mac' is still valid

2021-09-09 21:37:07  Mountpoint '/System/Volumes/Data' is still valid

2021-09-09 21:37:07  Backup failed (303: BACKUP_FAILED_PREFLIGHT_STAGE_GATHER_EVENTS)

Any thoughts are greatly appreciated.

Thanks.

Thanks so much. Just tried the thinning command and remaining steps. Unfortunately, same result. Pasting the logs below in the hopes that someone might have an idea. At this point, I have received a new backup drive, but if it is TM that is corrupt, I'm thinking that opening and installing that drive will have no impact but will have cost me $180. Wondering if I should:

1.) Try the new drive and hope that it works (just doesn't make logical sense that it would), but I don't claim to understand how all this works.

2.) Revert using the TM backup from right before I upgraded to Big Sur (which seemingly has it's own risks)

3.) Use something other than TM for backup (major disappointment).

4.) Take to the Apple store for evaluation.

5.) Some other plan, not currently evident.

Appreciate all the patient support from this group. This is very stressful.

Thanks.

Logs attached as additional text due to character limits.

I am using Big Sur. Interestingly, cannot find a folder called Containers by searching through the file directory. When I use the Go to folder "~/Containers", I get the message: The folder can't be found. Could it be hidden, somehow? Don't know that I've ever used that command in Finder before, but I'm entering it exactly as noted above.

great thanks - plenty of options there ;-)

will give them a try tomorrow

plenty of space on both drives (1tb free on backup & 2tb free on mac)

as I said above - problem has been solved

Good to hear! Thanks. 👍

I just upgraded to Big Sur and immediately, this problem began. Apple support could not resolve and suggested a new Hard Drive. Did the snapshots deletion work? Thanks.