Which process is locking a file on Windows ?

List processes locking a file by file path sub-string:

Command line

1. Install the handle tool from the Sysinternals suite
2. Run handle -u [file path sub-string] in a cmd.exe window

The -u option includes the user owning the process.

Example:

handle -u "some.pdf"
AcroRd32.exe   pid: 11208  type: File  localnet\oliver 
244: C:\Users\Public\Documents\some-folder\some.pdf

GUI

1. Download Sysinternals Process Explorer
2. Menu : Find – “Find Handle or DLL …”