Newtonsoft.json: InvalidProgramException "Cannot create boxed ByRef-like values" for netcoreapp2.1

[springy76]

I changed the TargetFramework of an unit test from netcoreapp2.0 to netcoreapp2.1 without any further changes and this error happened on serializing:

Result StackTrace:  
at Newtonsoft.Json.Serialization.ExpressionValueProvider.GetValue(Object target)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.CalculatePropertyValues(JsonWriter writer, Object value, JsonContainerContract contract, JsonProperty member, JsonProperty property, JsonContract& memberContract, Object& memberValue)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeDictionary(JsonWriter writer, IDictionary values, JsonDictionaryContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.Serialize(JsonWriter jsonWriter, Object value, Type objectType)
   at Newtonsoft.Json.JsonSerializer.SerializeInternal(JsonWriter jsonWriter, Object value, Type objectType)
   at Newtonsoft.Json.JsonConvert.SerializeObjectInternal(Object value, Type type, JsonSerializer jsonSerializer)
   at MyUnitTest
--- End of stack trace from previous location where exception was thrown ---
----- Inner Stack Trace -----
   at System.Runtime.CompilerServices.RuntimeHelpers._CompileMethod(IRuntimeMethodInfo method)
   at System.Reflection.Emit.DynamicMethod.CreateDelegate(Type delegateType, Object target)
   at System.Linq.Expressions.Compiler.LambdaCompiler.CreateDelegate()
   at System.Linq.Expressions.Compiler.LambdaCompiler.Compile(LambdaExpression lambda)
   at Newtonsoft.Json.Utilities.ExpressionReflectionDelegateFactory.CreateGet[T](PropertyInfo propertyInfo)
   at Newtonsoft.Json.Serialization.ExpressionValueProvider.GetValue(Object target)
Result Message: 
Newtonsoft.Json.JsonSerializationException : Error getting value from 'Preamble' on 'System.Text.ConsoleEncoding'.
---- System.InvalidProgramException : Cannot create boxed ByRef-like values.

Googling this error only came up with this one.

[JamesNK]

Could you add a repro of the issue? I'm not even sure how to go about serializing ConsoleEncoding.

[springy76]

I'm not entirely sure where in my object graph a reference to ConsoleEncoding popped up, but the exception can be reproduced this way:

    object data = Console.InputEncoding;
    var json = JsonConvert.SerializeObject(data);
    Console.WriteLine(json);

The code above works on dotnetcoreapp1.0, dotnetcoreapp1.1, net4xx. (and fails on dotnetcoreapp2.0 with a different problem, so on that platform some other class which my code is serializing might not have a reference to ConsoleEncoding at all there yet).

But for sure the amount of these by-ref types (maybe a Span) will increase rapidly on netcore for constructor overloads etc.

[StefH]

I've the same issue (netcoreapp2.1) when serializing System.Text.UTF8Encoding.

The error message is

Error getting value from 'Preamble' on 'System.Text.UTF8Encoding'. ---> System.InvalidProgramException: Cannot create boxed ByRef-like values

[kierenj]

I have the same - as above - at runtime. My unit tests seem to serialise UTF8Encoding just fine, but at runtime, it fails on the preamble property (a ReadOnlySpan)

Edit: this was because my test project was still netcoreapp2.0. On netcoreapp2.1 it repro's each time

[JamesNK]

Fixed. ref struct properties values are skipped instead of throwing an error.