I have an argon running OS 4.0 that has twice now gotten a solid white LED. When it occurs all network activity is stopped, and some, but not all of the digital outputs that were previous on stay on.
The device appears unresponsive to input, so I perform a power cycle. After the power cycle the argon comes back to life and proceeds as though nothing was ever wrong.
This device started doing this last week, but has been running for a few months prior with no issues. The firmware version currently loaded had been running for upwards of a week prior to the issue with no problems, and now I have had the white LED issue twice in as many days.
There are a handful of other identical systems running this same firmware and none of the others exhibit this behavior.
Solid colors should not occur. The most common cause is that the device locked up with interrupts off. The color of the LED is the last color it was, so solid red (from SOS) or solid cyan are the most common, but it could be anything, including LED off.
Solid white should never occur because white is not a regular status LED color, except at boot. It’s possible that the device rebooted and then locked up, but this is unusual, except in the case of a power problem.
Since this is affecting only one device, and the firmware is working on other devices, I would first focus on a power issue. After that, the harder problem of locating possible locations for deadlock is the next thing.