Comment 1 for bug 1796245

I cannot replicate with that set of steps on my windows machine. Note
that the editor operates on a copy of the original book folder. Every
operation is performed on the copy. When you click save the original
folder is updated from the copy. SSo there is no question of calibre
deleting still open files.

The only suggestion I have is that you exclude whatever folder you are
using for the books from your antivirus/file sync type programs as these
can often hold a file open.

 status invalid