// GET api/values/5 public async Task <string> Get(string filter) { try { GraphServiceClient client = await MicrosoftGraphClient.GetGraphServiceClient2(); //var resultaat = await client.Users["db4fef52-9274-49e2-846c-1f325c4b9d7c"].Drive.Root.Children.Request().GetAsync(); var resultaat = await client.Users["db4fef52-9274-49e2-846c-1f325c4b9d7c"].Request().GetAsync(); //var resultaat = await client.Request("https://graph.microsoft.com/v1.0/me/").GetAsync(); Debug.WriteLine(resultaat.ToString()); return(resultaat.ToString()); } catch (MsalUiRequiredException) { return("request fout"); // The application does not have sufficient permissions // - did you declare enough app permissions in during the app creation? // - did the tenant admin needs to grant permissions to the application. } catch (MsalServiceException ex) when(ex.Message.Contains("AADSTS70011")) { return("request fout"); // Invalid scope. The scope has to be of the form "https://resourceurl/.default" // Mitigation: change the scope to be as expected ! } }