Time Machine doesn't complete B/up.
Time Machine doesn't complete B/up. First Aid tested external HD and said it appears to be fine.I have copied files to the drive with no problem. Rebooted, restarted. My Mac, no help. removed external drive from USB hub, plugged directly into mac air (2011). Time Machine still won't complete the backup.
Message I receive is "An error occurred while copying files. The problem may be temporary. If the problem persists, use Disk Utility to repair your backup disk." Did all that.
MacBook Air 13", macOS 10.13