My understanding of Time Machine is that it clears out old backups to make room for new ones. I’m backing up about 1.1TB of data (my iMac’s SSD and an external SSD with our Photos library on it) to a 2TB SSD.
Time Machine is telling me there isn’t enough space on the Time Machine drive to continue backing up. I would think there would be space for at least one full snapshot and a few days (or even weeks, based on how little actually changes on the machine) of incremental snapshots.
Most of what I’m finding through DuckDuckGo tells me to go into the time machine drive and manually delete folders, starting with the oldest. This seems dicey to me.
As far as I know, the only safe way to delete backups is to use the tmutil program from the command line. That said, I’ve had frequent enough issues with TimeMachine backup corruption that I only use it to restore accidentally deleted files, and otherwise don’t rely on it for backups.
That said, the best bet going forward is to go to TimeMachine Preferences and have it exclude folders that you don’t need to have backed up, like Downloads or any folders having only temporary files. Anything that is archival is best backed up some other way and not by TimeMachine. Then just be resigned to occasionally having to erase the drive and start over.
I run two local backups using Arq and Time Machine. About a month ago Time Machine ran out of room and deleted ALL the backups. I’ve had TM fail all kinds of ways but this was new. Must be a new feature Apple is rolling out.
I’ve been having the same issue and our IT person encouraged me to go into Time Machine and clear old files. I get the message from CleanMyMac, too and haven’t had great success with getting CMM and TM to talk to each other.