JWT错误->无效的签名c＃.net核心

Question

我正在处理JWT验证模块，并在JWT.io中收到无效签名错误。

我的令牌：

            var claimRoles = "Admin"; 
            var tokenDescriptor = new SecurityTokenDescriptor
            {
                Subject = new ClaimsIdentity(new Claim[]
                {
                    new Claim("UserId", user.Id.ToString()),
                    new Claim("Roles", claimRoles)
                }),
                Expires = DateTime.UtcNow.AddMinutes(60),
                SigningCredentials = new SigningCredentials(new SymmetricSecurityKey(Encoding.UTF8.GetBytes(_appSettings.JWT_Secret)), SecurityAlgorithms.HmacSha256)
            };

            var tokenHandler = new JwtSecurityTokenHandler();
            var securityToken = tokenHandler.CreateToken(tokenDescriptor);
            var token = tokenHandler.WriteToken(securityToken);
            return Ok(new { token });

我的startup.cs

    var key = Encoding.UTF8.GetBytes(Configuration["ApplicationSettings:JWT_Secret"]);

    services.AddAuthentication(x => 
    {
        x.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
        x.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
        x.DefaultScheme = JwtBearerDefaults.AuthenticationScheme;
    }).AddJwtBearer(x=> {
        x.RequireHttpsMetadata = false;
        x.SaveToken = false;
        x.TokenValidationParameters = new TokenValidationParameters
        {
            ValidateIssuerSigningKey = true,
            IssuerSigningKey = new SymmetricSecurityKey(key),
            ValidateIssuer = false,
            ValidateAudience = false,
            ClockSkew = TimeSpan.Zero 
        };
    });

我的不记名令牌之一：

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJVc2VySWQiOiJhNzQ3Y2U5Mi1kMjhhLTQwZGYtYjU0MS00Zjg5MjI1NmEzNzgiLCJSb2xlcyI6IkFkbWluIiwibmJmIjoxNTc0MTE2MDUwLCJleHAiOjE1NzQxMTk2NTAsImlhdCI6MTU3NDExNjA1MH0.Unxv9bQOPDYn_IAi7GLBv8eZEy1f1L1-yH-VP_c-iSU

我在做什么错了？