6.5 update 5

While logging into iVend POS, it doesn't go for Transaction screen but screen get blank with white color. iVend POS log file displays error message:

<Version>6.5.5</Version>
<Category>ERROR</Category>
<Time>10:59:45 AM</Time>
<Message>
Object reference not set to an instance of an object.
</Message>
<ExceptionInfo>
<Type>System.NullReferenceException</Type>
<Message>
Object reference not set to an instance of an object.
</Message>
<Source>CXSRetailPOS</Source>
<TargetSite>Boolean HandleTipplePoint(CXS.SubSystem.Till.Till)</TargetSite>
<StackTrace>
at CXSRetailPOS.POSUILogic.HandleTipplePoint(Till till) at CXSRetailPOS.POSUILogic.ShowTillSelectionView() at CXSRetailPOS.POSUILogic.ShowTimeClockView() at CXSRetailPOS.POSUILogic.LoginViewEventHandler(Object sender, EventArgs args) at CXSRetailPOS.TouchScreenLoginView.FireDone(EventArgs args) at CXSRetailPOS.TouchScreenLoginView.DoElectronicLogin(String data) at CXSRetailPOS.TouchScreenLoginView.SetupView(String electronicId) at CXSRetailPOS.POSUILogic.ShowLoginView()
</StackTrace>

With such error message, suggest to check if any open till still available with previous business date in Store MC Till Screen.

If yes, then need to close it from Store MC . If getting error to close it, check its Till tables in Store database base.