I noticed that if I in robotstudio download EIO.cfg where some signal has a Category or SignalLabel with just line (-) I get a RobAPI when doing warmstart.
So for example this signal definition causes RobAPI exeption:
-Name “doStart” -SignalType “DO” -Unit “Virtual”
-SignalLabel “-” -UnitMap “1” -Category “-” -Access “All”
In a real robot those signal definitions files work just fine.