Passing null to a method argument that does not accept null values.
Thrown when a null reference is passed to a method that requires a non-null object for parameter validation.
Passing null parameters to framework methods like `string.Join()`, `Convert.ToDateTime()`, or LINQ methods.
1using System;2using System.Collections.Generic;3using System.Linq;4 5public class Program {6 public static void Main() {7 List<string> names = null;8 var count = names.Count(); // Throws ArgumentNullException!9 }10}1using System;2using System.Collections.Generic;3using System.Linq;4 5public class Program {6 public static void Main() {7 List<string> names = null;8 9 // Fix: Use null-conditional operator10 int count = names?.Count() ?? 0;11 Console.WriteLine($"Name count: {count}");12 }13}Simulate standard system builds to trigger compiler trace records and track memory crashes locally.
LINQ extension methods like `Enumerable.Count()` throw `ArgumentNullException` immediately if the source collection reference is `null`.