c# - your - Graph API-Insufficient privileges to complete the operation

register your application insufficient privileges to complete the operation. (4)

When trying to access the Graph Service Client using I am receiving the error :

Code: Authorization_RequestDenied
Message: Insufficient privileges to complete the operation.

After researching this error the most common solution was to set the permissions for the API. This had already been done and has permissions to read basic/full profiles.

I've delete and re-added the APIs.

Below is the code in my AzureAuthenticationProvider class which inherits from IAuthenticationProvider:

public class AzureAuthenticationProvider : IAuthenticationProvider
    private string _azureDomain = "myDevDom.onmicrosoft.com";

    public async Task AuthenticateRequestAsync(HttpRequestMessage request)
            string clientId = "2b823c67-1b0d-4a10-a9e1-737142516f5q";
            string clientSecret = "xxxxxx";

            AuthenticationContext authContext = new AuthenticationContext("https://login.windows.net/" + _azureDomain + "/oauth2/token");

            ClientCredential credentials = new ClientCredential(clientId, clientSecret);

            AuthenticationResult authResult = await authContext.AcquireTokenAsync("https://graph.microsoft.com/", credentials);

            request.Headers.Add("Authorization", "Bearer " + authResult.AccessToken);
        catch (Exception ex)

I've tried changing the client secret to an invalid Id and it threw an error, so the client key is correct. I've also tried to verify that the access token is valid by altering the access token, this also returns a error.

The above code seems to work fine.

Below is the code where I'm trying to access Azure AD:

public async Task<IGraphServiceUsersCollectionPage> GetUsersByLastName(string lastname)  
    GraphServiceClient graphClient = new GraphServiceClient(new AzureAuthenticationProvider());
    string filter = String.Format("startswith(surname, '{0}')", lastname);
    IGraphServiceUsersCollectionPage users = await graphClient.Users.Request().Filter(filter).GetAsync(); //Fails on this line
    return users;

Any help is much appreciated, and thanks in advance for any help.

Make sure click "Grant Permissions" and than Yes for all users accounts.

For me the key to solve this problem was hint:

To use the Graph API with your B2C tenant, you will need to register a dedicated application by using the generic App Registrations menu (All Services and there it is by default not Favourite starred) in the Azure Portal, NOT Azure AD B2C's Applications menu. You can't reuse the already-existing B2C applications that you registered in the Azure AD B2C's Applications menu.

Find more on page AD B2C aPI access demo

It seems like your application is not having enough rights to access AD information. You can follow the steps mentioned in below link/article to login to Azure portal and see if your application has got enough privileges to access AD.



Also I hope, the "authResult.AccessToken" is not null in your case. One thing, the second link above is having very detailed explanation on application access rights to AD. could be of help to you.

Please refer to below steps :

  1. From your screenshot , seems you grant Read and write directory data application permission for Windows Azure Active Directory(azure ad graph api) . Since you are using microsoft graph (https://graph.microsoft.com/) , you need to grant application permission for Microsoft Graph :

  2. Since you are admin in your AAD, You could grant permission for users in organization by click Grant permission button shown in above screenshot .

  3. Then you could use your code (client credential flow to get the token) and query users information . If you check the claims in access token issued by azure ad , you could find Directory.Read.All permission in roles claim .