This error occurs during a COC update. It is caused when a connection between the software and the database gets closed prematurely. It appears to be a problem with the application server (Tomcat). We are publishing some new code tonight (Dec 6) that will reduce (not eliminate, but reduce) the number of times it happens. Technically, its not a problem with NeoNexus code, but a problem with the Tomcat connection pool manager (sort of like a bug in Microsoft Access software straight out of the box from Microsoft). We are searching for a way to deal with it.
In the meantime, when that happens, you have to click on the COC item in the left menu, search for the COC you were just working on, and go back to it again. The good news is that the updates seem to occur; you just have to go back to the COC to view the changes.
Sorry for your pain. IF you can figure out a sequence of events that triggers this error consistently, please let me know (I’ll send you a bonus gift!). The frustrating part so far is it seems to happen randomly, so it is harder to track down.