Bundle UniFi Controller 5.9.29. SeeHERE for controller release notes.
Bundle UniFi Protect 1.4.2. *UCK-G2-Plus only.
Fix a rare bug where the device may reset to defaults when in the Rack Mount accessory.
Various fixes for Cloud Key G2 Rack Mount accessory.
Miscellaneous bug fixes and improvements.
How to update the latest firmware:
From UniFI Controller: Settings -> Maintenance -> CHECK FOR UPDATES (in CloudKey Firmware section) -> APPLY UPDATE
From UniFi Cloud Key WebUI: Manage Cloud Key > Settings > Firmware > Update Manually. From here you can either paste the URL, or if you downloaded the binary you can select the file locally on your computer.