After upgrading to firmware version 1.255, take the following precautions:
Note: Ubiquiti now uses ui.com . If the above returns 404, use the archive path: Upgrade Firmware Version 1.255 Ubnt Download UPD
Invalid Image Error: This usually means the file was corrupted during download or you downloaded the version for the wrong hardware model. Re-download the file and try again. After upgrading to firmware version 1