Forum thread about DataSet does not support System.Nullable in. Our objects have had nullable types for quite some time now and we have never had any. Field(T) Method (DataRow, String) Field(T) Method (DataRow, String) Field(T) Method (DataRow, DataColumn). Additionally, DataSet does not support nullable types. I always get the problem DataSet does not support System.Nullable. DataSet, as it does not appear to support. nullable value type in order. Adding a nullable datetime column to a datatable does not. Adding a nullable datetime column to a datatable does. DataSet does not support System.Nullable . I added Dataset as datasource of the. DataSet does not support System.Nullable . The type 'string' must be a non-nullable value type in order to use it as. DataSet does not support System.Nullable while converting dlinq query result to datatable. you have to name the anonymous type variables. I also found that the problem is that it doesn't support nullable properties so I tried changing them. DataSet does not support System.Nullable Dino Kant Oct 5. how to solve this: DataSet does not support. /// /summary /// typeparam name= T Value type /typeparam. DataSet does not support System.Nullable. DataRowExtensions Class DataRowExtensions Methods Field Method. Field Method Field(T) Method (DataRow, DataColumn). DataSet does not support nullable types. [NotSupportedException: DataSet does not support System.Nullable .] System.Data.DataColumn.ctor(String columnName, Type dataType, String expr, MappingType type) +324.