Time Machine backups failed after simple Sonoma update

Mac Sonoma - I had started a new time machine a few weeks ago.

  • I believe there was many gigabytes of free space on the external SSD drive.

This morning I updated to the newest Sonoma version.

  • then I ran Time Machine back up after completion.

  • for some reason the latest backup was not able to complete and the error said that the external SST did not have enough free space (there was still 50 gigs free).

  • on the disk was only one back up instead of the 10 or 15 previous days which had been deleted for some reason.

  • nothing else had changed on my drive except the macOS Sonoma update.

  • it seems there’s no reason that it would’ve used up so many gigabytes after a simple update.

I thought Time Machine was supposed to remove old backups when space was needed?

Q: so I’m curious why this happened and if it has happened to anyone else?

Q: does anyone know any way to recover the existing Time machine back up?

Thanks – Dave

Speculation: Time Machine removed as much as it could in order to do the new backup, but the post upgrade backup is large enough that it would exceed the remaining space and TM won’t remove the last good backup.

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Hi - That is a good guess and makes sense.

The Apple senior tech suggested that the update from Sonoma 14.7.xxx to 14.7.1 was a relatively small security related update and should have not caused any major issues.

After running disk utility first aid, what we saw was that volume was using 1.4 TB however the time machine folder was just using 550 gigs - so there was a lot of missing Space and oddly that volume only had 50 gigs free…

His best assessment was simply that time machine “got corrupted for unknown reasons” (not all that helpful from a senior technician) - and that I ultimately reformatted that volume and will start fresh.

The only thing that the Apple tech recommended interest here - was to run disk utility from recovery mode. He suggested that it’s quicker and more reliable and safer to do it that way. Ultimately he decided that the time machine back up simply got corrupted. Then we reformatted the drive to start fresh.

Since I don’t use time machine much, my question is if the drive fills up - is Time Machine supposed to automatically remove the oldest Data to make room for new things? Also, Will you see older Folders in the main window vanish as they are not needed - or does it leave them in place?

This has been a recurring problem for me over many years with a variety of disk drives. So much so that I stopped using Time Machine. Now I keep a spinning hdd connected to my Mac and let Carbon Copy Cloner run hourly backups to it. Problem solved.

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