DO NOT USE THIS UNLESS YOU REALLY KNOW WHAT YOU ARE DOING

The "Upgrade File Structure" button allows you to re-run a version 3.10 to 4.00 upgrade that was, for some reason, skipped when the board was initially upgraded. The only known case under which this is known to happen is when a version 4.0 board is installed fresh, and then data files from version 3.10 are manually loaded on top of the version 4.0 board (which really takes a special effort).

Although it is believed to be safe to run this operation even on a working version 4.0 board, it is not recommended. If you believe that you need to run this, it is suggested that you contact DiscusWare's support to confirm it before you do so. Or, at least make a full backup of your board before doing it.