When I am trying to create a GNT, i am getting this error and the GNT is not getting created. How to solve that?
The reason behind that is possibly the use of List in the data types while creating GNT like the snapshot below where the data type is double,
To solve that in the datatype's, instead of using Object, you need click on that filed and select the datatype as Obj.
Once the datatype is changed to Object, you will be able to create the GNT properly.