Why is List<string> being saved in application settings but LinkedList<string> isn't?

Question

This is my Settings.setting file:

 <Setting Name="AutoCompleteList" Type="System.Collections.Generic.LinkedList&lt;string&gt;" Scope="User">
      <Value Profile="(Default)" />
 </Setting>

and this is my Settings.Designer.cs:

public global::System.Collections.Generic.LinkedList<string> AutoCompleteList {
   get {
       return ((global::System.Collections.Generic.LinkedList<string>)(this["AutoCompleteList"]));
   }
   set {
       this["AutoCompleteList"] = value;
   }
}

Programs.cs

class Program
{
    private static LinkedList<string> _autoCompleteList;
    static void Main()
    {
        _autoCompleteList = new LinkedList<string>((new[] {"one", "two"}));
        
        Settings.Default.AutoCompleteList = _autoCompleteList;
        Settings.Default.Save(); //Nothing is saved. (Silently and without any error)
        
        _autoCompleteList = Settings.Default.AutoCompleteList; //null
    }
}

If I use List<string> instead of LinkedList<string> all things work; but I need LinkedList, because it makes it easier to access the previous and next elements. Yes. It's possible using List in app settings and load it into a LinkedList at runtime, but I want to know why LinkedList can't be saved in app settings.

Also I should have made it clear that all my settings are scoped as "User"

Answer 1

Linked list is a data structure that is implemented in memory only because each element also linked to another element. That's why it can't be saved. It just can be implemented in memory.