Give this a shot. In Visual Studio 2010, open your app.config or web.config file. Go to the XML menu and select Create Schema. This action should create a new file called "app.xsd" or "web.xsd". Save that file to disk. Go back to your app.config or web.config and in the edit window, right click and select properties. From there, make sure the xsd you just generated is referenced in the Schemas property. If it‘s not there then add it. That should cause those messages to disappear.
原文：http://www.cnblogs.com/sungang3225/p/3982797.html