Macintosh System Software: Use Installer, Don‘t Drag-Copy

Is it really necessary to use the Installer application to put a new System on a Macintosh? What's wrong with just dragging over a good System Folder from another computer?
Drag copying System Folders is not an acceptable method of replacing System files. You must use the Installer to get a complete and successful installation of all necessary visible and invisible System files. There are hooks and patches to the ROM that can be part of the System only if the Installer is used.

If you have a System that was installed by drag-copying, we suggest that you trash it and install a fresh System Folder using the Installer program.
Published Date: Feb 18, 2012