FreeFileSync Forum

Do you mean in conjunction with FreeFileSync, or on its own just to fix permissions?

In looking at - https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/robocopy - it could be this:

/secfix Fixes file security on all files, even skipped ones

I have a couple of Windows servers on a domain that on which FFS is mirroring (one-way) from an older to new machine. This includes a general shared directory tree as well as personal user folders. I had started this syncing before finding the Tools > Copy DACL, SACL, Owner, Group checkbox ...