可能有多种原因导致此问题，但以下是一些常见的

1. 确保在Startup.cs文件中正确配置了Authorization和Authentication中间件。可以使用以下代码：

services.AddAuthentication(options => { options.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme; options.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme; }).AddJwtBearer(options => { options.RequireHttpsMetadata = false; options.SaveToken = true; options.TokenValidationParameters = new TokenValidationParameters { ValidateIssuerSigningKey = true, IssuerSigningKey = new SymmetricSecurityKey(Encoding.ASCII.GetBytes(Configuration.GetSection("Jwt:Key").Value)), ValidateIssuer = false, ValidateAudience = false }; });

services.AddAuthorization(options => { options.AddPolicy("Admin", policy => policy.RequireClaim("Role", "Admin")); });

2. 确保有效的JWT token已正确传递。可以使用以下代码：

[Authorize] public IActionResult Get() { var identity = HttpContext.User.Identity as ClaimsIdentity; IList claims = identity.Claims.ToList();

return new JsonResult(new
{
    Username = claims[0].Value,
    Email = claims[1].Value
});

}

3. 确保在前端（例如React或Angular）正确设置了Authorization标头，如下所示：

axios.defaults.headers.common["Authorization"] = "Bearer " + token;

通过遵循上述步骤，您应该可以解决“AuthenticationScheme：Bearer未经身份验证”的问题。