what causes a null exception code example

Example 1: exception is null

//Bug with VS: Exception e == null
//Happens when multiple catch variables are the same
//an example of the solution:
try
{
    // do something
}
catch (WebException webEx) // using a variable named 'webEx' for this catch
{
    Logger.Log("Error while tried to do something. Error: " + webEx.Message); // <-
}
catch (Exception ex) // using a DIFFERENT variable for this one
{
    Logger.Log("Error while tried to do something. Error: " + ex.Message);
}

Example 2: null exception

using System;
using System.Collections.Generic;

public class Example
{
   public static void Main()
   {
      List<String> names = new List<String>();
      names.Add("Major Major Major");
   }
}