Unexpected Null Reference handling When Deserializing Complex XML with XmlSerializer in C#
I'm collaborating on a project where I'm building a feature where I've searched everywhere and can't find a clear answer. I'm experiencing a frustrating null reference exception when trying to deserialize a complex XML structure into a C# object using `XmlSerializer`. The XML I'm working with looks like this: ```xml <Library> <Books> <Book> <Title>Effective C#</Title> <Author>Bill Wagner</Author> <ISBN>978-0323683684</ISBN> </Book> <Book> <Title>Design Patterns</Title> <Author>Erich Gamma</Author> <ISBN>978-0201633610</ISBN> </Book> </Books> </Library> ``` I have defined the following C# classes: ```csharp [XmlRoot("Library")] public class Library { [XmlArray("Books")] [XmlArrayItem("Book")] public List<Book> Books { get; set; } } public class Book { public string Title { get; set; } public string Author { get; set; } public string ISBN { get; set; } } ``` When I run the deserialization code like this: ```csharp var serializer = new XmlSerializer(typeof(Library)); using (var reader = new StringReader(xmlString)) { var library = (Library)serializer.Deserialize(reader); } ``` I keep getting a `NullReferenceException` at the line where I try to access `library.Books`. I've checked that the `xmlString` contains valid XML, but it seems like the `Books` property is not being populated. I've also confirmed that the `XmlSerializer` is not throwing any explicit errors during deserialization. I’ve tried adding `[XmlElement]` attributes to the `Books` property and ensuring that there are no mismatches in the XML structure and the class definitions, but the scenario continues. I'm using .NET 5.0. Any ideas on what could be causing this behavior? Am I missing something in my XML mapping or configuration? I'm working on a CLI tool that needs to handle this. Any help would be greatly appreciated! I've been using C# for about a year now. Am I approaching this the right way? I'm working in a Ubuntu 22.04 environment. I'd really appreciate any guidance on this.