使用User.ReadBasic.All从Azure AD中读取用户时出现权限问题？

对于此问题，您似乎无权获取用户。您可以参考图api的文档，需要如下所示的权限：

因此，请转到在您的天蓝色广告中注册的应用程序，然后单击“ API权限”，然后在其中添加权限。

After add the permissions, please do not forget click "Grand admin consent for xxx".

For the question why it still failed when you change the Users to me. You use client credential flow to do authentication to request the graph api, you just provide the information of clientId, tenantId and clientSecret. So it doesn't contain a user(or yourself) information. So you can't use .Me. If you want to use .Me, you can use password grant flow. It contains the user information, so system know who is .Me.

================================Update==============================

如果您要使用委托权限（例如User.ReadBasic.All），则不能使用client_credential。现在您的代码使用client_credential流，访问令牌不包含用户身份。我在下面提供了一个用户名/密码流示例（并使用委托权限User.ReadBasic.All）供您参考f：

在已注册应用的“ API权限”标签中，我只添加一个权限User.ReadBasic.All。

代码如下图所示：

using Microsoft.Graph;
using Microsoft.Graph.Auth;
using Microsoft.Identity.Client;
using System;
using System.Security;

namespace ConsoleApp3
{
    class Program
    {
        static async System.Threading.Tasks.Task Main(string[] args)
        {
            IPublicClientApplication publicClientApplication = PublicClientApplicationBuilder
            .Create("<clientId>")
            .WithTenantId("<tenantId>")
            .Build();

            string[] scopes = new string[] { "https://graph.microsoft.com/.default" };

            UsernamePasswordProvider authProvider = new UsernamePasswordProvider(publicClientApplication, scopes);

            GraphServiceClient graphClient = new GraphServiceClient(authProvider);

            var str = "<your password>";
            var password = new SecureString();
            foreach (char c in str) password.AppendChar(c);

            var users = await graphClient.Users.Request().WithUsernamePassword("<your account/email>", password).GetAsync();

            Console.WriteLine(users.Count);
        }
    }
}

并且在运行代码之前，您需要做一次“同意使用该应用程序”。您需要按以下方式浏览网址：https://login.microsoftonline.com/<tenantId>/oauth2/v2.0/authorize?client_id=<clientId>&response_type=code&redirect_uri=<redirectUri>&response_mode=query&scope=openid https://graph.microsoft.com/.default&state=12345在浏览器中，页面将显示为：

单击“接受”，然后可以运行代码以获取成功的用户列表。