For an overview of the Warning & Error Codes have a look here. LINK Updaten
If you can't start an optimization you might have missed to set up all options. Please take care of messages in the infocenter at the very bottom of the Graphics Window!
You can find warning and error messages during the optimization in the log-file in the result tab.
Differentiated log files are saved in the project folder in your workspace (in the folder the optimization was started in). Further information here.
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