I have coded RestAPI with .NET . I am using Postman to test the API. It is giving me successful http request for GET and DELETE. But throwing error for PUT and POST request.

Below are the codes I am using to create RestAPI.

Code: Player.cs

using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace UnityRestAPI.Contracts
{
    [JsonObject, Serializable]
    public class Player
    {
        public int Id { get; set; }

        public string FullName { get; set; }

        public float Score { get; set; }
    }
}

Code: PlayersController.cs

using System.Collections.Generic;
using System.Linq;
using Microsoft.AspNetCore.Mvc;
using UnityRestAPI.Contracts;

namespace UnityRestAPI.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class PlayersController : Controller
    {

    private static List<Player> Players = new List<Player>()
    {
        new Player
        {
            Id = 1,
            FullName = "Michael Jordan",
            Score = 1000
        },
        new Player
        {
            Id = 2,
            FullName = "Steve Jobs",
            Score = 2000
        },
        new Player
        {
            Id = 3,
            FullName = "Carton John",
            Score = 3000
        },
    };


    // GET api/players
    [HttpGet]
    public JsonResult Get()
    {
        return Json(Players);
    }

    // GET api/players/5
    [HttpGet("{id}")]
    public JsonResult Get(int id)
    {
        Player player = Players.Single(p => p.Id == id);
        return Json(player);
    }

    // POST api/players
    [HttpPost]
    public JsonResult Post([FromBody]Player newPlayer)
    {
        Players.Add(newPlayer);
        return Json(Players);
    }

    // PUT api/players/5
    [HttpPut("{id}")]
    public JsonResult Put(int id, [FromBody] float newScore)
    {
        Player player = Players.Single(p => p.Id == id);
        player.Score = newScore;
        return Json(player);
    }

    // DELETE api/players/5
    [HttpDelete("{id}")]
    public void Delete(int id)
    {
        Player player = Players.Single(p => p.Id == id);
        Players.Remove(player);
    }
}
}

RestAPI GET request in Postman: Successful request

Postman Error for POST request in Postman: Input not valid