A Microsoft file hosting and synchronization service.
I had the same problem - I emptied my personal vault but still OneDrive would constantly stop with:
Then my OneDrive just crashed with Exception code: 0xc000027b
I had to re-install and restart my OneDrive, and it began re-syncing all my local files.
As luck would have it, this time OneDrive ignored my (already empty) personal vault, and it hasn't bothered me since.
But it was sheer luck.
It appears Vlase's suggestion (to reset OneDrive) has the same benefit.