http://developers.de/blogs/andreas_lehmann/archive/2008/08/13/breaking-change-in-the-in-the-sspinegotiatedovertransport-wcf.aspxRegarding to my previous post on breaking changes in SP1 for Visual Studio 2008 and the .NET Framework 3.5 I found another breaking change in the in the SspiNegotiatedOverTransport authentication mode (WCF). When WSHttpBinding , WS2007HttpBinding , orenCommunityServer 2008 SP1 (Build: 30619.63)