This is an NVML (the Nvidia hardware monitoring library) internal error. We have seen similar errors on our GTX1060s. Additional symptoms include high CPU usage (either by the miner or the MSI Afterburner). The same problems were also observed with Claymore's miner on the same rig. The short term-solution is to restart the rig (not just the miner) but the only long-term solution is to lower the memory overclock a little. We have found that even 20-30 MHz lower memory clocks completely solve the problem. Or you can continue mining and ignore the errors but the high CPU usage can be a real PITA when trying to control the rig via VNC or TeamViewer.
In my case, Afterburner completely freezes, can't do anything with it, but the mining continues. Remote desktop works.
And yes, I tried more aggressive overclocks, but I wasn't saved to an Afterburner profile, so a restart would solve this problem for me, and a stable Afterburner profile is selected by FarmWatchBot.
I need to revert this function because this is not critical error and can be solved by user.
Some users with high overclock reported that they just ignored this error and mining as well.
I believe this error is not counted.
unable to get fan speed - Unknown Error (999)
Official answer by PhoenixMiner
In my case, Afterburner completely freezes, can't do anything with it, but the mining continues. Remote desktop works.
And yes, I tried more aggressive overclocks, but I wasn't saved to an Afterburner profile, so a restart would solve this problem for me, and a stable Afterburner profile is selected by FarmWatchBot.