After upgrade to Yosemite Time Machine says "Disk Full" even if there's 350GB free space I upgraded to Yosemite yesterday, and just now I got a Time Machine alert


  Disk is Full


although there are 350+ GB on the backup disk according to Finder. It said it had deleted an old backup (boo).

Just now I did a manual backup (from the TM preferences panel) and it backed up 2 MB to the free 350GB disk and all was fine.

What gives?  What can I do to make TM happy?
If on top of your Mac's hard drive, you are also backuping an external USB drive, you may want to check this thread: https://discussions.apple.com/message/27031297