app.config "Could not find schema information" after converting to Visual Studio 2010 / .Net 4.0

Question

After upgrading my project to Visual Studio 2010 and .Net 4.0, my app.config file generates these messages upon building the project:

• Could not find schema information for the element 'supportedRuntime'.
• Could not find schema information for the attribute 'version'.
• Could not find schema information for the attribute 'sku'.

Here is my entire app.config file:

<?xml version="1.0"?>
<configuration>
  <startup>
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0,Profile=Client"/>
  </startup>
</configuration>

If I create a new VS2010 project and literally copy/paste the same app.config file, I receive no such messages.

Obviously these messages are not causing any runtime problems, but they are still annoying and disconcerting.

How do I fix whatever problem is making these messages appear?

I see the answer at http://stackoverflow.com/questions/229155/app-config-configsections-custom-settings-can-not-find-schema-information, but I see nowhere in the properties list to enter the path to the schema.

Thanks.

Answer 1

Are you sure the conversion went ok? Maybe the correct target framework wasn't configured. Open your project properties and check if the target framework is actually .NET Framework 4 or .NET Framework 4 Client Profile.

Answer 2

I changed the schema from DotNetConfig to DotNetConfig35 and it took care of the issue. This is available in the properties of the app.config file.