.NET 3.5 SP1 Breaking Change to WCF

I walked into a booby-trap with .NET 3.5 SP1. Here are the details. You receive a 401 authentication error when you upgrade your server running WCF service to .NET 3.5 SP1. The WCF run-time now requires an identity to be passed in on the call. The identity or SPN is not verified for authenticity, it just needs to be present. You can fix the issue from code or by inserting the identity tag into the url. The authentication failure is triggered if all of the conditions are met The scenario uses ClientCredentialType.Windows, which specifies the Negotiate authentication scheme. The scenario uses … Continue reading .NET 3.5 SP1 Breaking Change to WCF