SharePoint Dragons

Nikander & Margriet on SharePoint

Authentication when using the SharePoint client object model

Normally, when you need to log in using a specific credential set in the SharePoint client object model, you’ll have to provide the correct credentials to authenticate to the SharePoint site collection, like so:

NetworkCredential credentials = new NetworkCredential(“username”, “pwd”, “domain”);

ClientContext context = new ClientContext(“http://thesitecollection”);

context.Credentials = credentials;

This won’t work if you have a claims based site set up supporting both Windows and forms authentication. See for more about setting that up. Instead, you need to set up the appropriate HTTP headers to disable Forms authentication, and it’ll work again:

ClientContext clientContext = new ClientContext(“http://thesitecollection“);clientContext.ExecutingWebRequest += new EventHandler<WebRequestEventArgs>(clientContext_ExecutingWebRequest);

Web site = clientContext.Web;




static void clientContext_ExecutingWebRequest(object sender, WebRequestEventArgs e){

    e.WebRequestExecutor.WebRequest.Headers.Add(“X-FORMS_BASED_AUTH_ACCEPTED”, “f”);


See for more info.

6 responses to “Authentication when using the SharePoint client object model

  1. Pingback: Forms authentication using the Client Object Model « SharePoint Dragons

  2. Pavan September 12, 2012 at 11:22 am

    Thanks, this was what I was looking for

  3. LyLV March 21, 2013 at 4:33 am

    LyLV: Thanks so much!

  4. Kyle January 29, 2015 at 12:30 am

    Great quick find, thanks much..

  5. Andrew Weddle June 30, 2015 at 3:36 am

    Life saver. This has been irritating me for a few days off and on!

  6. ltd July 17, 2015 at 2:18 am

    Awesome!! I struggled for hours getting the 403 Forbidden error however this fixed it! Many thanks!

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