Error: Another CarMaker model is already running, must be stopped first

Why? 

• This error appears if a CM4SL simulation is started, while a simulation with another model is already running

What to check if this error occurs?

• How was the simulation started (TestManager, Start button in CM-GUI, Play button in Simulink, ScriptControl, etc.)?
• What is the status of CM GUI and what status is shown in MATLAB ?
• Has the previous simulation really ended? Check for the SIM_END Log entry in the SessionLog.
• Try the following commands (in italics) in the MATLAB command window
  cmcmd runningmodel : returns info about the currently running model
  cmcmd simstate :  returns the actual simulation state
• Does cmcmd runningmodel give a meaningful model name as result? Is it the name of the previously ended model?