c# - 通过用户管理器设置 RefreshToken 的 ASP.NET Core 用户管理器问题

Question

我在 ASP.NET Core 中有这个 web api 方法：

        [HttpPost("Refresh")]
        public async Task<IActionResult> Refresh([FromBody]TokenRefreshDto tokenRefreshDto)
        {
            var principal = _userService.GetPrincipalFromExpiredToken(tokenRefreshDto.Token);
            var username = principal.Identity.Name; 

            var user = await _userService.GetUserByUserName(username);
            if (user == null || await _userManager.GetAuthenticationTokenAsync(user,"Default","RefreshToken") != tokenRefreshDto.RefreshToken) return BadRequest();

            var newJwtToken = await _userService.GenerateJwtToken(user);

            await _userManager.RemoveAuthenticationTokenAsync(user, "Default", "RefreshToken");
            var newRefreshToken = await _userManager.GenerateUserTokenAsync(user, "Default", "RefreshToken");
            await _userManager.SetAuthenticationTokenAsync(user, "Default", "RefreshToken", newRefreshToken);

            return new ObjectResult(new
            {
                token = newJwtToken,
                refreshToken = await _userManager.GetAuthenticationTokenAsync(user, "Default", "RefreshToken")
            });
        }

当我尝试刷新 RefreshToken 时，会出现以下错误：

InvalidOperationException: The instance of entity type "User" cannot be tracked
        because another instance with the same key value for "Id" is already being tracked

我的 User 类是从 IdentityUser 派生的：

public class User : IdentityUser<int>
    {
        public string Name { get; set; }
        public string LastName { get; set; }
        public string MobilePhone { get; set; }
        public string Address { get; set; }
        public Guid? ShopId { get; set; }
        public DateTime LastActive { get; set; }
        public virtual Shop Shop { get; set; }

    }