Specific machines fail to connect to Team Foundation Service with the error TF400813: Resource not available for anonymous access. Client authentication required. The stack trace in Test Studio application log follows. As a work-around one can install the following updates: 1. http://visualstudiogallery.msdn.microsoft.com/a37e19fb-3052-4fc9-bef7-4a4682069a75 2. http://www.microsoft.com/en-us/download/details.aspx?id=29082 [01/17 13:27:16,Telerik.TestStudio.exe(4648:5),TeamFoundationServer] TFSServer.ConnectToServer() : EXCEPTION! (see below) Situation: Exception connecting to TFS server Outer Exception Type: Microsoft.TeamFoundation.TeamFoundationServiceUnavailableException Message: Team Foundation services are not available from server [url]. Technical information (for administrator): TF400813: Resource not available for anonymous access. Client authentication required. HRESULT: 0x80131600 (Official ID (if app.) = COR_E_APPLICATION, Error Bit = FAILED, Facility = FACILITY_URT, Code = 5632) Call Stack: at Microsoft.TeamFoundation.Client.TeamFoundationSoapProxy.ThrowIfServiceUnavailable(HttpWebResponse response, TfsConnection tfs, String nameOrUri) at Microsoft.TeamFoundation.Client.TeamFoundationSoapProxy.GetWebResponse(WebRequest request) at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters) at Microsoft.TeamFoundation.Proxy.BisRegistrationServiceProxyWsdl.GetRegistrationEntries(String toolId) at Microsoft.TeamFoundation.Proxy.BisRegistrationProxy.GetRegistrationEntries(String toolId) at Microsoft.TeamFoundation.Proxy.BisRegistrationService.RefreshMemoryCache() at Microsoft.TeamFoundation.Proxy.BisRegistrationService.RefreshCachesIfNeeded(Boolean direct) at Microsoft.TeamFoundation.Proxy.BisRegistrationService.GetRegistrationEntries(String toolId) at Microsoft.TeamFoundation.Framework.Client.PreFrameworkServerDataProvider.FindServiceLocation(String serviceType, String toolId) at Microsoft.TeamFoundation.Framework.Client.PreFrameworkServerDataProvider.LocationForCurrentConnection(String serviceType, Guid serviceIdentifier) at Microsoft.TeamFoundation.Client.TfsConnection.EnsureProviderConnected() at Microsoft.TeamFoundation.Client.TfsConnection.<EnsureAuthenticated>b__0() at Microsoft.TeamFoundation.Client.TfsConnection.UseCredentialsProviderOnFailure(Action action) at Microsoft.TeamFoundation.Client.TfsConnection.EnsureAuthenticated() at ArtOfTest.Common.TFSClient.TFSServer.ConnectToServer(IServerInfo server)