[Negitivefrags]

Open up "Resource Monitor" and go to the "Disk" tab. Under "Disk Activity" you can see all open file handles.

[kevin_thibedeau]

Certainly not a sensible solution like having a dialog button that gives you all the relevant information immediately and empowers you to solve the problem without a goose chase.

[coldtea]

Which are thousands...

[psykotic]

You need the Sysinternals utilities to make life tolerable: https://docs.microsoft.com/en-us/sysinternals/downloads/hand... from the command line or Ctrl-F in https://docs.microsoft.com/en-us/sysinternals/downloads/proc... if you prefer a GUI. They do a brute-force search over the open handles in all processes, but it's effective.

[noisem4ker]

I prefer this utility: http://www.emptyloop.com/unlocker/

It lets you see which process locked a file, and optionally remove the lock.