Unifi u6+ failing to upgrade

I have quite a few sites where some Unifi U6+ Access Points fail to upgrade with a generic update failed message.

Marquis WiFi Vergaderruimte 4 update failed.

I’ve tried everything, from ssh‘ing, factory resetting with set-default, to manually upgrading with upgrade, etc.

Nothing worked. I thought I had a bunch of bad APs (and many had their warranty expire by a few weeks or months).

As a last resort, I decide to reach out to Ubiquiti’s support. First line wasn’t very helpful, but as the case was escalated, I’ve managed to recover and properly update the APs.

The trick is to ssh into the device and run the following code:

curl -fs https://dl.ui.com/firmwares/uap/jw/U6Rescue.sh | sh

The device will reboot and pop by up in the dashboard after 2-3 minutes. Then try to update again, and all should work.

Not really sure what’s going on here but …