Json.net can't deserialize simple struct, throws System.NullReferenceException

[sake402]

Description

System.Text.Json is unable to deserialize a very basic struct

Reproduction Steps

using System;
					
public class Program
{
	
    public enum LengthUnitTypes
    {
        None,
        m,
        cm,
        mm,
        um,
        @in,
        ft,
        km,
        mi
    }
	public struct Length{
            public Length()
            {
            }

            public Length(double value, LengthUnitTypes unit)
            {
                Value = value;
                Unit = unit;
            }

            public double Value { get; set; } = 0;
            public LengthUnitTypes Unit { get; set; } = LengthUnitTypes.None;
	}
	public static void Main()
	{
		var l = new Length();
		var json = System.Text.Json.JsonSerializer.Serialize(l);
		Console.WriteLine(json);
		l = System.Text.Json.JsonSerializer.Deserialize<Length>(json);
		Console.WriteLine("Hello World");
	}
}

Result

{"Value":0,"Unit":0}
Unhandled exception. System.NullReferenceException: Object reference not set to an instance of an object.
   at ValueSetter(Object , Double )
   at System.Text.Json.Serialization.Metadata.JsonPropertyInfo`1.ReadJsonAndSetMember(Object obj, ReadStack& state, Utf8JsonReader& reader)
   at System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1.OnTryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value)
   at System.Text.Json.Serialization.JsonConverter`1.TryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value)
   at System.Text.Json.Serialization.JsonConverter`1.ReadCore(Utf8JsonReader& reader, JsonSerializerOptions options, ReadStack& state)
   at System.Text.Json.JsonSerializer.ReadFromSpan[TValue](ReadOnlySpan`1 utf8Json, JsonTypeInfo jsonTypeInfo, Nullable`1 actualByteCount)
   at System.Text.Json.JsonSerializer.ReadFromSpan[TValue](ReadOnlySpan`1 json, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Deserialize[TValue](String json, JsonSerializerOptions options)
   at Program.Main()
Command terminated by signal 6

See fiddle here https://dotnetfiddle.net/n21G3a

Expected behavior

No exception. And if something is wrong with class/struct declaration, throw a more descriptive exception.

Actual behavior

Throws null reference

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

[ghost]

Tagging subscribers to this area: @dotnet/area-system-text-json, @gregsdennis
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

System.Text.Json is unable to deserialize a very basic struct

Reproduction Steps

using System;
					
public class Program
{
	
    public enum LengthUnitTypes
    {
        None,
        m,
        cm,
        mm,
        um,
        @in,
        ft,
        km,
        mi
    }
	public struct Length{
		public Length()
        {
        }

        public Length(double value, LengthUnitTypes unit)
        {
            Value = value;
            Unit = unit;
        }

        public double Value { get; set; } = 0;
        public LengthUnitTypes Unit { get; set; } = LengthUnitTypes.None;
	}
	public static void Main()
	{
		var l = new Length();
		var json = System.Text.Json.JsonSerializer.Serialize(l);
		Console.WriteLine(json);
		l = System.Text.Json.JsonSerializer.Deserialize<Length>(json);
		Console.WriteLine("Hello World");
	}
}

Result

{"Value":0,"Unit":0}
Unhandled exception. System.NullReferenceException: Object reference not set to an instance of an object.
   at ValueSetter(Object , Double )
   at System.Text.Json.Serialization.Metadata.JsonPropertyInfo`1.ReadJsonAndSetMember(Object obj, ReadStack& state, Utf8JsonReader& reader)
   at System.Text.Json.Serialization.Converters.ObjectDefaultConverter`1.OnTryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value)
   at System.Text.Json.Serialization.JsonConverter`1.TryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value)
   at System.Text.Json.Serialization.JsonConverter`1.ReadCore(Utf8JsonReader& reader, JsonSerializerOptions options, ReadStack& state)
   at System.Text.Json.JsonSerializer.ReadFromSpan[TValue](ReadOnlySpan`1 utf8Json, JsonTypeInfo jsonTypeInfo, Nullable`1 actualByteCount)
   at System.Text.Json.JsonSerializer.ReadFromSpan[TValue](ReadOnlySpan`1 json, JsonTypeInfo jsonTypeInfo)
   at System.Text.Json.JsonSerializer.Deserialize[TValue](String json, JsonSerializerOptions options)
   at Program.Main()
Command terminated by signal 6

See fiddle here https://dotnetfiddle.net/n21G3a

Expected behavior

No exception. And if something is wrong with class/struct declaration, throw a more descriptive exception.

Actual behavior

Throws null reference

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

Author:	sake402
Assignees:	-
Labels:	area-System.Text.Json, untriaged
Milestone:	-

[EgorBo]

Likely dupe of #62983 (fixed in 7.0)

[eiriktsarpalis]

Can confirm that the issue has been resolved with the latest builds in .NET 7

[danmoseley]

Should we consider for backport?

[EgorBo]

Should we consider for backport?

I asked that in #62989 but since nobody responded I didn't file one

[eiriktsarpalis]

I'm guessing it got dropped because it happened over the holidays. I think we should backport it.

[EgorBo]

Ok, I'll file a backport