Upgrade Firmware Version 1.255 Ubnt -upd- [extra Quality] Download Guide

Check the official release notes for version 1.255 to see if there are specific "leap" requirements (e.g., needing to be on a specific older version before jumping to 1.255).

If the controller method fails, you can push the update manually: Upgrade Firmware Version 1.255 Ubnt -UPD- Download