Unable to get attachments from a group conversation

Question

I want to get the attachments of a post that is part of a group conversation.
The application has the following permissions: Type: Application, Group.Read.All, Group.ReadWrite.All

            app = ConfidentialClientApplicationBuilder.Create(config.ClientId)  
                .WithClientSecret(config.ClientSecret)  
                .WithAuthority(new Uri(config.Authority))  
                .Build();  

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


            LogHelper.Info("Conversations...");  
            await apiCaller.CallWebApiAndProcessResultASync($"{config.ApiUrl}v1.0/groups/{groupId}", result.AccessToken,  
                 Display);  

             LogHelper.Info("Posts...");  
             await apiCaller.CallWebApiAndProcessResultASync($"{config.ApiUrl}v1.0/groups/{groupId}/threads/{threadId}/posts/", result.AccessToken,  
                 Display);       
  
             LogHelper.Info("Attachments...");  
             await apiCaller.CallWebApiAndProcessResultASync($"{config.ApiUrl}v1.0/groups/{groupId}/threads/{threadId}/posts/{postId}/attachments", result.AccessToken,  
                 Display);  

I get the group and the posts. But it has an error for the attachments:
Failed to call the web API: Forbidden
Content: {"error":{"code":"ErrorAccessDenied","message":"Access is denied. Check credentials and try again."}}

Unable to get attachments from a group conversation

According to the documentation, if I have the rights to the posts and the group then I should have the rights to the attachments.
https://learn.microsoft.com/en-us/graph/api/post-list-attachments?view=graph-rest-1.0&tabs=http

Why don't I have the rights?

Answer 1

Hello @Olivier-7208 ,

Thank you for reaching Microsoft.

I can see that you are using application permission for this API, this works with getting the posts of the specified thread. But as mentioned in the document, retrieving the attachments from a post works with only Delegated permissions.

As seen from the above table, application permission is not supported to get the post attachments. I suggest you to consent the required delegated permission and use the API.

Documentation: https://learn.microsoft.com/en-us/graph/api/post-list-attachments?view=graph-rest-1.0&tabs=http

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