Time Machine can't back up to MacBook Pro High Sierra
I keep getting this message:
"Time Machine could not create a local snapshot to back up from because there was insufficient free space on the source volume(s)."
Yet I get this also on same dialog box: Latest successful backup: August 20, 2020
I have plenty of room on my new 4TB external hard drive. I have 3GB available on a 122GB computer.
Why do I keep getting the message?
MacBook