This exception is thrown when you try to dereference a null pointer (for example, accessing an instance field on an object reference that currently points to no instance).

public class NullReferenceException : SystemException {
// Public Constructors
   public NullReferenceException( );
   public NullReferenceException(string message);
   public NullReferenceException(string message, Exception innerException);
// Protected Constructors
   protected NullReferenceException(System.Runtime.Serialization.SerializationInfo info,
        System.Runtime.Serialization.StreamingContext context);
}

Hierarchy

Object Exception(System.Runtime.Serialization.ISerializable) SystemException NullReferenceException