Would this happen to be (ick...) Microsoft Windows?   ;-)

If so, then not only should you use File::Find, but you should also cache all of the filenames found, into an array, first.   Then, go back and “run the list” of filenames that you just found.

The file-scanning primitives in Windows are easily flummoxed by any sort of file-operation that occurs in the meantime.   Therefore, “search first, ask questions later.”