根据YamlDotNet的所有者aubry的说法，issue here声明KeyValuePair<,>不受支持，也不会受到支持。然而，他在同一问题下的回应中进一步指出，通过添加自定义INodeDeserializer可以轻松实现。但是，由于他所包含的示例不适用，我将在这里提供一个更准确的实现。

using System;
using System.Collections.Generic;

using YamlDotNet.Core;
using YamlDotNet.Core.Events;
using YamlDotNet.Serialization;

internal class KeyValuePairNodeDeserializer : INodeDeserializer
{
    public bool Deserialize(IParser parser, Type expectedType, Func<IParser, Type, object> nestedObjectDeserializer, out object value)
    {
        if (expectedType.IsGenericType && expectedType.GetGenericTypeDefinition() == typeof(KeyValuePair<,>))
        {
            parser.Consume<MappingStart>();

            var pairArgs = expectedType.GetGenericArguments();

            object key = null;
            object val = null;

            if (parser.Accept<Scalar>(out _))
                key = nestedObjectDeserializer(parser, pairArgs[0]);

            if (parser.Accept<Scalar>(out _))
                val = nestedObjectDeserializer(parser, pairArgs[1]);

            value = Activator.CreateInstance(expectedType, key, val);

            parser.Consume<MappingEnd>();
            return true;
        }

        value = null;
        return false;
    }
}

现在您可以注册您的自定义INodeDeserializer如下：

var deserializer = new DeserializerBuilder()
    .WithNodeDeserializer(new KeyValuePairNodeDeserializer())     // Register here.
    .WithNamingConvention(UnderscoredNamingConvention.Instance)
    .Build();