I have done Time Machine backups to an external drive with my Mac plugged in and it appears to complete but the next time I begin a backup, I get a message that my previous backup was not completed because the computer was NOT plugged in.
I have done Time Machine backups to an external drive with my Mac plugged in and it appears to complete but the next time I begin a backup, I get a message that my previous backup was not completed because the computer was NOT plugged in.
MacBook Air 13″, macOS 11.6