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User profile for user: Mark Fusco
Mark Fusco Author
User level: Level 1
38 points

Time Machine Fail Due to a Snapshot of an External Disk Could Not Be Created

Updated to 12.5.1 yesterday. Now I'm getting an error that one of my external drives can't be backed up because a snapshot of that drive can't be created. TM was working perfectly up until the update. Just prior to the update I moved two folders from one external drive to the other external drive TM is complaining about. It was about 297 GB of data, with 296 of it in one folder.


Not sure if the movement of data and then a fairly quick start of installing of 12.5.1 created a problem or not. I've tried to do all the solutions I could find. Some of which are no longer valid under 12.5.1. But no success. Here is what I've tried:


  • Find the snapshot via terminal and delete. Not successful as I really don't see one for my specific drive. I used another command to try to delete all snapshots but Terminal wasn't having it.
  • Deleted the last backup in the TM drive.
  • Rebooted the computer several times
  • Eject and remounted the offending drive multiple times
  • Turn off Automatic Updates, leave for for over an hour, then turn back on and initiate backup. Multiple times.
  • Boot into Safe Mode and attempt to start backup
  • Find the Backups DB on the TM drive. No longer in Finder from what I can tell - turned on hidden files


Short of reformatting my TM drive and starting over, I can't think of anything else to do. I've rarely had TM issues, but when I do it seems like I have to resort to the "nuclear option" of wiping the TM drive and starting over. I have over 5 TB of data and I'd rather not go through a multi-day process. I do have an online backup so I'm not worried about how long it takes to do the new initial backup, I just don't want to have to do that.

iMac 27″, macOS 12.5

Posted on Aug 24, 2022 3:15 PM

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User profile for user: Mark Fusco
Mark Fusco Author
User level: Level 1
38 points

Posted on Aug 30, 2022 7:38 AM

So the solution was downloading the online backup of the two folders that had missing data and re-formatting the drive that had an issue. TM is working as it should. This is not the first time having an online backup of my files has saved me. Sometime weird things happen.

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User profile for user: leroydouglas
leroydouglas
Community+ 2024
User level: Level 10
188,640 points

Aug 25, 2022 8:53 AM in response to Mark Fusco

Mark Fusco wrote:

• Updated to 12.5.1 yesterday. Now I'm getting an error that one of my external drives can't be backed up because a snapshot of that drive can't be created. TM was working perfectly up until the update. Just prior to the update I moved two folders from one external drive to the other external drive TM is complaining about. It was about 297 GB of data, with 296 of it in one folder.

Not sure if the movement of data and then a fairly quick start of installing of 12.5.1 created a problem or not. I've tried to do all the solutions I could find. Some of which are no longer valid under 12.5.1. But no success. Here is what I've tried:

Find the snapshot via terminal and delete. Not successful as I really don't see one for my specific drive. I used another command to try to delete all snapshots but Terminal wasn't having it.
• Deleted the last backup in the TM drive.
• Rebooted the computer several times
• Eject and remounted the offending drive multiple times
• Turn off Automatic Updates, leave for for over an hour, then turn back on and initiate backup. Multiple times.
• Boot into Safe Mode and attempt to start backup
• Find the Backups DB on the TM drive. No longer in Finder from what I can tell - turned on hidden files

Short of reformatting my TM drive and starting over, I can't think of anything else to do. I've rarely had TM issues, but when I do it seems like I have to resort to the "nuclear option" of wiping the TM drive and starting over. I have over 5 TB of data and I'd rather not go through a multi-day process. I do have an online backup so I'm not worried about how long it takes to do the new initial backup, I just don't want to have to do that.



Trouble Shooting Time Machine

Time Machine troubleshooting on Mac - Apple Support



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User profile for user: Mark Fusco
Mark Fusco Author
User level: Level 1
38 points

Aug 25, 2022 7:13 PM in response to Barney-15E

Not in this case from what I can see. The drive that a snapshot cannot be taken of is a 4 TB drive that has various video files and other files for the creation of my videos and it has 2.58 TB available. TM was making regular hourly backups of all drives ( 1 internal and 4 external) and then didn't after the 12.5.1 update. The TM drive has 7.22 TB available.


I confirmed that this 4 TB drive is the issue by being able to have TM do a backup when that 4TB drive is not connected. When it completed that backup and I plugged the 4 TB drive back in I got the same failed snapshot error.

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User profile for user: Mark Fusco
Mark Fusco Author
User level: Level 1
38 points

Aug 26, 2022 5:02 AM in response to Barney-15E

Overnight I had copied all the files from the drive giving me a problem to another drive that has enough space to handle it. I saw your suggestion this morning to run First Aid. Ran First Aid at your suggestion. It found a snapshot error and could not repair it.


Compared files between the drives and found that a significant amount of data did not transfer. Found the two folders where files didn't completely transfer. Tried to do another transfer of files of each folder and got an error (Error -43 if I remember). Attempted to restore via TM, but it wouldn't work. It locked up on one occasion. tried to open one of the files and that didn't work.


Not sure if these new issues are as a result of running First Aid or not. If I had not run it I would image I would have had the same problem trying to copy, restore, open the files. My last option AFAIK is to use my online backup to restore the files that didn't transfer over.


I have to go to work so I'll see if you or anyone else has a different suggestion. From what I can tell from all of this, I'll have to restore from my online backup, reformat the problem drive and then restore the files that I want it to have. Hopefully that will resolve it.


Not sure what exactly caused this snapshot error considering TM had completed its hourly backups successfully just prior to updating the OS.

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Time Machine Fail Due to a Snapshot of an External Disk Could Not Be Created

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