Recovering Ubiquiti Unifi cloud key controllers that are offline

You will lose access to UniFi Management Dashboard https://unifi.ubnt.com when your Unifi cloud key goes offline or shows offline after the firmware upgrade. A typical example involves corrupted firmware updates, network issues, config changes or simply getting stuck after re-booting. I have worked with several small businesses on this issue. Sometimes re-booting solves the issues, but sometimes it doesn't. I had to wait between 30 minutes to up to 2 hours one time depending on the time of day, which is why I ended up contacting their "UniFi 24/7 live tech support". If you re-fresh your browser, you may be thrown out and have to restart the session. Below is what I did to make this work.

There are a few things you need to know, one is that you should make a backup of your configuration. If you don't, and for some reason, if you have still had access to the cloud key via ssh, then download the backup to your local computer. I am using a process here that sometimes picks up auto backup, and sometimes it doesn't. Ensure that the cloud key and other Unifi devices are on the same network. A third thing you may need is the UniFi discovery plugin, which I use in Chrome and helps find the Cloud key IP address if it changes, although this is not required since you can find it via DHCP, smart switches, or routers with MAC and IP information.

/data/autobackup is the location of the autobackup

Here's how to do a factory reset if you have access to your device via a browser or ssh. You can also use a paper clip small hole on the key to perform a hard reset, which will reset the device to its default state after a few seconds.

Option 1: via GUI web browser

Log in with user/password or default should be (user: ubnt and password: ubnt) at cloud key's IP address.  Click Maintenance>Reset To Defaults after logging in.

Option 2: via SSH

Login then run command: ubnt-systool reset2defaults

Once you done the factory reset process using option 1, 2 or hard reset

Then login back via browser, default login user/pass:

User: ubnt

Pass: ubnt

In order to restore, you must first stop the UNIFI service (since the server is running, Restore will be grayed out).

Click Restore from auto backup or a file you have on your local computer after stopping the Unifi service.

Confirm the restore by clicking OK.

Once the restore is complete, you may need to restart the Unifi service or it will reboot automatically

Then go to URL of your Unifi cloud key

You will have 3 options:

1 Restore from the backup file

2.  List backup if it detects, then you just choose

3.  Configure new setup

Click on the "Confirm" button once you have selected your restore option

and you will see "The system is being restored.".  We will restart the controller shortly.

As soon as it has restarted, you can log in again as normal.  The upgrade can then be installed.

UniFi Management Dashboard https://unifi.ubnt.com should have your Ubiquiti WiFi controller back online now.