Cloud key firmware from 5.12.22 to 5.12.35

From version
Controller: 5.12.22 (Build: atag_5.12.22_12966)
CLOUD KEY FIRMWARE: UCKP.apq8053.v1.1.0.aa44aee.190826.2316

Upgrade to new version
Controller: 5.12.35 (Build: atag_5.12.35_12979)
CLOUD KEY FIRMWARE: UCKP.apq8053.v1.1.6.c289a3c.191031.0851

Steps:

# ssh ubnt@${CONTROLLER_IP_ADDRESS}
# cd /tmp
# wget https://dl.ui.com/unifi/5.12.35/unifi_sysvinit_all.deb
# dpkg -i unifi_sysvinit_all.deb
(Reading database ... 31139 files and directories currently installed.)
Preparing to unpack unifi_sysvinit_all.deb ...
Unpacking unifi (5.12.35-12979-1) over (5.12.22-12966-1) ...
Setting up unifi (5.12.35-12979-1) ...
Processing triggers for systemd (241-5~bpo9+1) ...
UniFi-CloudKey-Gen2-Plus:/tmp# rm -f unifi_sysvinit_all.deb
UniFi-CloudKey-Gen2-Plus:/tmp# reboot

Access again the web interface of Unifi controller and the software should be updated.

Good Resources:
1. https://community.ui.com/releases/UniFi-Network-Controller-5-12-35/45726736-ee4c-4172-877a-a2303f5d3627

3. https://help.ubnt.com/hc/en-us/articles/360012282453-UniFi-How-to-Install-Upgrade-the-UniFi-Network-Controller-Software

4. https://www.youtube.com/watch?v=Z3q10J9dgjk&feature=youtu.be