Lots of errors are usually accompanied by the affected die showing it's not running with 0v 0a on the advanced page.

I've had that a few times as I have been tweaking the voltages and speeds to get the best out of mine.

When it happens a 'reboot' won't usually fix it, so I would give the affected die more volts and/or drop the speed, apply the settings then physically power off the miner, most times it then comes back to life