Error code 32 when multiple threads use `fs::rename` on the same file.

[tlehman]

Error code 32 when multiple threads use `fs::rename` on the same file.

[Lastique]

If the file is opened without the necessary sharing permission (see CreateFile documentation for dwShareMode) then MoveFileExW will fail with ERROR_SHARING_VIOLATION. I'm guessing, at least FILE_SHARE_READ | FILE_SHARE_DELETE share mode must be used on every handle for the file for MoveFileExW to succeed (FILE_SHARE_READ would be necessary if MoveFileExW falls back to CopyFile+DeleteFile implementation).

Boost.Filesystem doesn't keep file handles for files across function calls, other than directories that are used during directory iteration. Even then, the library code currently enables both FILE_SHARE_READ and FILE_SHARE_DELETE for handles it opens. So I strongly suspect that either your application opens a handle to the file without one of those sharing permissions, or there is another process in the system that does so. Note that this can truly be any process on the system, including e.g. antivirus software.

I remember there were fixes in Boost.Filesystem regarding file sharing permissions some time ago. It is likely that that was after Boost 1.73. It's difficult to tell for sure as there were too many changes since that release. I recommend you try with the latest Boost release. However, the requirement that all other handles for the file must have the necessary sharing permissions is still in effect, and there's nothing I can do to circumvent it. That's just how Windows works.

PS: The SO answer is only partially true. Sure, you can "fix" the problem by closing all other handles to the file. But the actual problem is the lack of the necessary sharing permissions on the handles. Without the permissions, the problem will still reproduce whenever the offending handle happens to exist while you're attempting to move the file.