SharePoint Dragons

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 https://sharepointdragons.com/2012/01/30/claims-in-sharepoint-2010/ 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;

clientContext.Load(site);

clientContext.ExecuteQuery();

 

static void clientContext_ExecutingWebRequest(object sender, WebRequestEventArgs e){

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

}

See http://social.technet.microsoft.com/Forums/en-US/sharepoint2010programming/thread/16cd0e26-8f3b-4ef2-bac4-c2c59849ab96 for more info.