System.NotSupportedException：不支持“System.Action”实例的序列化和反序列化。 路径：$.MoveNextAction

Question

I am following a simple tutorial on .NET 6 and it should work really simple, but apparently I get the exception. The sample code is the following:

        public async Task<ServiceResponse<List<GetCharacterDto>>> GetAllCharacters()
        {
            var response = new ServiceResponse<List<GetCharacterDto>>();
            var dbCharacters = await _context.Characters.ToListAsync();
            response.Data = dbCharacters.Select(c => _mapper.Map<GetCharacterDto>(c)).ToList();

            return response;
        }

The code in GetCharacterDto is

    public class GetCharacterDto
    { 
        public int Id { get; set; }
        public string Name { get; set; } = "Frodo";

        public int HitPoints { get; set; } = 100;

        public int Strength { get; set; } = 10;

        public int Defense { get; set; } = 10;

        public int Intelligence { get; set; } = 10;

        public RpgClass Class { get; set; } = RpgClass.Knight;
        
    }

RpgClass is

[JsonConverter(typeof(JsonStringEnumConverter))]
    public enum RpgClass
    {
        Knight = 1,
        Mage = 2,
        Cleric = 3
    }

The exception System.NotSupportedException: Serialization and deserialization of 'System.Action' instances are not supported. Path: $.MoveNextAction. System.NotSupportedException: Serialization and deserialization of 'System.Action' instances are not supported. Path: $.MoveNextAction. is thrown right at var dbCharacters = await _context.Characters.ToListAsync();

If I call it synchronously _context.Characters.ToList() it works alright, but can't get it to work asynchronously.

I have both .NET 5 SDK and .NET 6 SDK installed, if that could be a potential issue.

Much appreciated for your helpful responses.

Answer 1

I was missing an await in the controller where I was calling the GetAllCharacters() method.