Not encountered this one before, but on a search I see it's common. Only backed up a few weeks ago so usually only see that for a few minutes when backing up, so I know it's not right. Have tried all searches of web hacks like deleting the 'in progress' file, and letting spotlight reindex with restart, and then tried the excluding from spotlight etc., but nothing seems to work. Any known problems with Sierra and this, as I've not had this before with any previous OS. And the last time I did it, I was on Sierra and it seemed to work fine. There have been no major changes to the MBP since the last back up so wondered if anyone can help before I deleted the whole HD, which is what I had to do when changed to Sierra and it takes forever. Thanks