Time Machine Backup Failing When Target Disk Full

[37Shannon]

I thought that Time Machine was supposed to delete older files when the backup disk became full. But in my case, TM just dies with "Backup Failed". The Time Machine disk is almost, but not quite, full.

I've had this problem ever since I've been using Time Machine, I just never asked about it, because I would just delete some older files myself and Time Machine would start working again. My primary disk is 1TB with only 283Gb used, and my Time Machine disk is an external disk with 655Gb capacity and 50Gb available.

Why does this do the way it does?

 

[37Shannon]

Additional information: I was running originally from Macintosh HD, with Time Machine running. I then turned Time Machine automatic backups off and cloned that drive to an external disk named Catalina. I then turned Time Machine automatic backups back on. Does Time Machine consider identically-named files from two different disks to be two different files? If it does, this would explain my disk-full scenario but still not why Time Machine just doesn't delete the oldest files.

 

[Elrich]

I have the same question. On my old MacBook Pro, I didn't have this problem, but since I switched to a MacBook Air last spring, it happens every time I get about a month's worth of backups on the external drive, and the only way I can find to delete them is put them in the Trash in the Finder, and then empty the Trash. Which is annoying, a) because it takes a long time, and b) because invariably it will prompt me about files that it says it can't delete because they're in use. (I did try going into TimeMachine, but navigation is puzzling and I can't seem to go back farther than "yesterday". )

Until I changed Macs, I assumed TimeMachine was deleting old backups on its own when the drive got full. There doesn't seem to be any such setting. Is this just how Time Machine is (now)??

 

[harrylarry]

I've had this problem for several years. I've just deleted the old backups myself. Always wondered why it didn't work as promised.