How to detect name of application that has locked File/Folder?

[j0nas]

You can use the free utility Handle to list/enum all handles (like opened file objects).

For many years ago, I posted a question about something like this:
Enum HANDLEs for current process
AdaraCD gave a good answer. I never got to implement it because I found out that I didn't actually need to enum handles for the project I was doing (so I never tried to code).

Another solution is to execute Handle.exe and parse the output (start the process and redirect the stdout with pipes). This is acutally a quite good solution I think, because Handle.exe is probably very good written and you don't have to deal with low-level stuff and O/S compatibility problems.