I was in the process of upgrading a few Unifi Access Point firmware’s and ran in to a problem where the AP’s would not (re)connect to the Unifi Controller when I initiated the firmware update. It was stuck in the update state without actually updating the firmware. The controller showed them as offline/updating.
It was still able to ping it and it was reachable over SSH.
I needed a way to update the firmware using SSH. I looked up the exact firmware download URL on https://www.ui.com/download/. I connected to the specific AP using SSH (Putty) and was able to perform the update manually by running the following command:
((`which nohup` /usr/bin/syswrapper.sh upgrade http://dl.ui.com/unifi/firmware/U7PG2/126.96.36.19933/BZ.qca956x.v188.8.131.5233.190518.0923.bin >/dev/null 2>/dev/null)&) ; sleep 1
This command took a few minutes to start running and successfully completed the firmware update. I was able to manage them again in the controller with it’s new firmware.
If the AP is on a low firmware level, it may come back with a error that it could not download the firmware because of a certificate error. In that case you can simply change https:// to http://.