cbot stops by itelsf after upgrade to 4.2

After upgrading to 4.2 from 4.1, my cbot now breaks and I get this error

30/08/2022 15:03:14.337 | cbotname, USDX, m15] crashed with error "Crashed in Positions.Opened event with NullReferenceException: Object reference not set to an instance of an object."

Here are the related code

        void Position_Opens(PositionOpenedEventArgs obj)
        {

            if (obj.Position.Label.Equals(_longlabel))
                _longopen = true;

            if (obj.Position.Label.Equals(_shortlabel))
                _shortopen = true;

        }

        protected override void OnStart()
        {
            Initialize();
            Positions.Opened += Position_Opens;
            Positions.Closed += Position_Closes;
            adx = Indicators.DirectionalMovementSystem(ADXPeriod);
        }

The problem doesnt happen onstart but it seems its related to positions

I have been using this cbot for a year without issues but just upgraded to 4.2 and since then it just stops by itself and I have to manually restart every day, sometimes multiple times a day.

Please is there something I need to change in the cbot?

Urgent help appreciated