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dwr130 Author

Level 1

29 points

Time Machine Backup Fails

I am using Catalina 10.15.6. I backup to an external SSD attached by USB to my computer. The backups up have been working fine but just started failing due to lack of space on the external drive. I know I can clear off my drive and start over. However, before I upgraded to Catalina, time machine would simply overwrite the oldest backup when the drive ran out of space. Why isn't this happening in Catalina, and is there anything I can do to fix this problem. Thanks for your help!

iMac 27″ 5K, macOS 10.15

Posted on Dec 4, 2020 6:01 PM

Top-ranking reply

John Galt

Level 10

146,384 points

Posted on Dec 5, 2020 6:27 AM

Time Machine segregated Catalina backups from systems earlier than it. If you were to investigate you may find a folder containing a Mojave backup that you probably no longer need, assuming you upgraded macOS from it to Cat a year or so ago.

The solution is to erase the backup drive and start a new set. If that is your only TM backup, I recommend having more than just one.

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Time Machine Backup Fails

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