I guess you are trying to backup Windows 10 64Bit, as in your first post?
Three things you should try.
1. Type vssadmin delete shadows /all from an elevated command prompt. This should clear the cached attempts.
2. Right click the start button and, in run, type services.msc Scroll down and change the "Volume Shadow Copy" to automatic.
3. Do you still have the folder "win.old. on the computer? This can cause the problem, also.