When I upgraded my ZD earlier from 10.1.2.0.251 to 10.1.2.0.318, everything works fine after a reboot. However, after an hour, when I try to access my ZD again, I got this error in the browser.

I've tried using a different browsers and rebooting it again to no avail. I've also tried this step via SSH:
Ruckus> enable
Ruckus# config
Ruckus (config)# certificate
Ruckus (config-certificate)# restore
Still can't get to access it, though the APs works fine. Have anyone encountered this issue?