Well, at first glance I would assume that there is an error with your COR module. But I think we need a bit more detail to actually provide some help. Have you tried restarting the apex and unplugging the COR and plugging it in again? Have you tried cleaning the pump? Exactly what does the error say? Can you post a screen shot of it? What is the pump doing now... is it still working or does it not even start? Were there any changes before you got this error?
Cor pump was cleaned in the last month. No issues in it's history to this point. I got an error while at work (Module error on Cor_3_1 (Volt)). It cleared in 6 minutes and has not returned. I cannot speak for what the pump did immediately before, during, or after the error as I was not there. Right now it shows 100% OK pulling 64 watts, 2814 RPM, & 55% on temp. I did not get a Hi_Sump alarm at any time so if it did shut down it didn't shut down long enough to raise the water level in the sump.
Since you got a VOLT error, it should be either an overvoltage or undervoltage problem.
Could be a transient issue with the driver, the energy bar, or even the incoming line voltage.