If you’re encountering the general error even with the models that had worked earlier, chances are that an RSM process was not properly terminated which may be preventing the solver to run anything new. Please try the following steps: – If you have any workbench sessions, please save the model and exit WB. – Open Windows Task Manager and look for the processes Ans.RSM.xxx Manually terminate them. – Open the WB session and open the RBD model that was running earlier and try solving it.