title: Microsoft Graph API Potential Throttling
body: <p>I've written a console app, that will be used to upload files to an Office 365 Unified Group. I'm using the Microsoft Graph API to get a reference to the drive under the group, and then upload files. I am using the Microsoft.IdentityModel.Clients.ActiveDirectory NuGet package for Authentication. This application needs to upload several thousand files, and I believe that I'm encountering some throttling issues.</p>
  
  <p>I am able to upload around 4000 files without any issues, but after that I begin to get 401 "Unauthorized" responses. At first I thought it was a token expiration issue, but I changed my code to get a brand new token if a 401 is encountered. I didn't initially suspect throttling issues, because I am not getting a 429 reponse error code (see: <a href="https://github.com/OfficeDev/microsoft-graph-docs/blob/master/content/overview/errors.md" rel="nofollow">https://github.com/OfficeDev/microsoft-graph-docs/blob/master/content/overview/errors.md</a>).</p>
  
  <p>Is it possible that too many requests to the Microsoft Graph API in some period of time could result in 401 Unauthorized error response messages?</p>
  
  <p>I'm making the upload requests sequentially (not in parallel), and I've added a 1 second pause between each request.</p>